ExamGuru Biology Class 12 WWW.EXAMSAKHA.IN

12 CBSE 2022-23 BIOLOGY (As per the Latest Syllabus issued by CBSE on April 21, 2022) Dr. Jasbir Singh MSc Zoology, PhD Full Marks Pvt Ltd (Progressive Educational Publishers) New Delhi-110002

Published by: 9, Daryaganj, New Delhi-110002 Phone: 011- 40556600 (100 Lines) Website: www.fullmarks.org E-mail: [email protected] © Publishers All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages. Branches: • Chennai • Guwahati Marketing Offices: • Ahmedabad • Bengaluru • Bhopal • Dehradun • Hyderabad • Jaipur • Jalandhar • Kochi • Kolkata • Lucknow • Mumbai • Patna • Ranchi NEW EDITION “This book is meant for educational and learning purposes. The author(s) of the book has/have taken all reasonable care to ensure that the contents of the book do not violate any existing copyright or other intellectual property rights of any person in any manner whatsoever. In the event the author(s) has/have been unable to track any source and if any copyright has been inadvertently infringed, please notify the publisher in writing for corrective action.”

Preface Biology-12 is based on the latest curriculum guidelines specified by the CBSE. It will certainly prove to be a torch-bearer for those who toil hard to achieve their goal. This All-in-one Question Bank has been developed keeping in mind all the requirement of the students for Board Examinations preparations like learning, practicing, revising and assessing. Salient Features of the Book: ●● Each chapter is designed in ‘Topic wise’ manner where each topic is briefly explained with sufficient Examples and Exercise. Exercise which covers Objective Type Questions and all the possible variety of Questions. ●● Answers with hints are provided separately after the exercise. ●● Previous years’ Board Questions have been covered in every chapter. ●● 1 Solved Sample Paper and 2 Unsolved Sample Papers are given with hints & answers for self assessment. ●● The book has been well prepared to build confidence in students. S uggestions for further improvement of the book, pointing out printing errors/mistakes which might have crept in spite of all efforts, will be thankfully received and incorporated in the next edition. —Publisher (iii)



Syllabus Time: 3 Hours Max. Marks: 70 Unit Title Marks VI Reproduction 16 VII Genetics and Evolution 20 VIII Biology and Human Welfare 12 IX Biotechnology and its Applications 12 X Ecology and Environment 10 Total 70 UNIT-VI REPRODUCTION Chapter-2: Sexual Reproduction in Flowering Plants– Flower structure; development of male and female gametophytes; pollination - types, agencies and examples; outbreeding devices; pollen-pistil interaction; double fertilization; post fertilization events - development of endosperm and embryo, development of seed and formation of fruit; special modes- apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit formation. Chapter-3: Human Reproduction– Male and female reproductive systems; microscopic anatomy of testis and ovary; gametogenesis - spermatogenesis and oogenesis; menstrual cycle; fertilisation, embryo development upto blastocyst formation, implantation; pregnancy and placenta formation (elementary idea); parturition (elementary idea); lactation (elementary idea). Chapter-4: Reproductive Health– Need for reproductive health and prevention of Sexually Transmitted Diseases (STDs); birth control - need and methods, contraception and medical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive technologies - IVF, ZIFT, GIFT (elementary idea for general awareness). UNIT-VII GENETICS AND EVOLUTION Chapter-5: Principles of Inheritance and Variation– Heredity and Variation: Mendelian inheritance; deviations from Mendelism - incomplete dominance, co-dominance, multiple alleles and inheritance of blood groups, pleiotropy; elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; Sex determination - in humans, birds and honey bee; linkage and crossing over; sex linked inheritance - haemophilia, colour blindness; Mendelian disorders in humans - thalassemia; chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes. Chapter-6: Molecular Basis of Inheritance– Search for genetic material and DNA as genetic material; Structure of DNA and RNA; DNA packaging; DNA replication; Central dogma; transcription, genetic code, translation; gene expression and regulation - lac operon; genome and human and rice genome projects; DNA fingerprinting. Chapter-7: Evolution– Origin of life; biological evolution and evidences for biological evolution (paleontology, comparative anatomy, embryology and molecular evidences); Darwin’s contribution, modern synthetic theory of evolution; mechanism of evolution - variation (mutation and recombination) (v)

and natural selection with examples, types of natural selection; Gene flow and genetic drift; Hardy - Weinberg’s principle; adaptive radiation; human evolution. UNIT-VIII BIOLOGY AND HUMAN WELFARE Chapter-8: Human Health and Diseases– Pathogens; parasites causing human diseases (malaria, dengue, chikungunya, filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ring worm) and their control; Basic concepts of immunology - vaccines; cancer, HIV and AIDS; Adolescence - drug and alcohol abuse. Chapter-10: Microbes in Human Welfare– Microbes in food processing, industrial production, sewage treatment, energy generation and microbes as bio-control agents and bio-fertilizers. Antibiotics; production and judicious use. UNIT-IX BIOTECHNOLOGY AND ITS APPLICATIONS Chapter-11: Biotechnology - Principles and processes– Genetic Engineering (Recombinant DNA Technology). Chapter-12: Biotechnology and its Application– Application of biotechnology in health and agriculture: Human insulin and vaccine production, stem cell technology, gene therapy; genetically modified organisms - Bt crops; transgenic animals; biosafety issues, bio piracy and patents. UNIT-X ECOLOGY AND ENVIRONMENT Chapter-13: Organisms and Populations– Population interactions - mutualism, competition, predation, parasitism; population attributes - growth, birth rate and death rate, age distribution. (Topics excluded: Organism and its Environment, Major Abiotic Factors, Responses to Abiotic Factors, Adaptations) Chapter-14: Ecosystem– Ecosystems: Patterns, components; productivity and decomposition; energy flow; pyramids of number, biomass, energy (Topics excluded: Ecological Succession and Nutrient Cycles) Chapter-15: Biodiversity and its Conservation– Biodiversity-Concept, patterns, importance; loss of biodiversity; biodiversity conservation; hotspots, endangered organisms, extinction, Red Data Book, Sacred Groves, biosphere reserves, national parks, wildlife, sanctuaries and Ramsar sites. (vi)

Question Paper Design Competencies 50% Demonstrate Knowledge and Understanding 30% Application of Knowledge / Concepts 20% Analyse, Evaluate and Create Note: • Typology of questions: VSA including MCQs, Assertion – Reasoning type questions; SA; LA-I; LA-II; Source based/ Case-based/ Passage-based/ Integrated assessment questions. • An internal choice of approximately 33% would be provided. Suggestive verbs for various competencies • Demonstrate, Knowledge and Understanding: State, name, list, identify, define, suggest, describe, outline, summarize, etc. • Application of Knowledge/Concepts: Calculate, illustrate, show, adapt, explain, distinguish, etc. • Analyze, Evaluate and Create: Interpret, analyse, compare, contrast, examine, evaluate, discuss, construct, etc. (vii)

D:\\EG_Biology-12\\Open_Files\\Ch-1\\Ch-1 O V E R V I E W O F A C H A P T E RReader’s Sign _______________________ Date __________ \\ 03-Aug-2022  Ved_Goswami   Proof-3 Biology XII 1 Sexual Reproduction in Flowering Plants Topics covered 1.1 Flower 1.2 Pre-Fertilization Events 1.3 Pollination 1.4 Double Fertilization 1.5 Seeds and Fruits C hapter map SEXUAL REPRODUCTION IN FLOWERING PLANTS D:\\EG_Biology-12\\Open_Files\\Ch-1\\Ch-1 Reader’s Sign _______________________ Date __________ \\ 04-Aug-2022  Ved_Goswami   Proof-3 Flower Structure Male and Female Structure Outbreeding • Calyx • Stamen • Pistil Devices • Corolla (i) Filament (i) Stigma • Androecium (ii) Anther (ii) Style • I nbreeding • Gynoecium (iii) Ovary depression Pollen — Pistil Pollination Development of an embryo sac Interaction (Megasporogenesis) • Type • Agencies • Compatible • A cell differentiates and becomes a megaspore Pollen and (i) Autogamy (i) Anemophily (Wind) mother cell. Megaspore mother cell divides by Stigma meiosis to form tetrad. Three cells degenerate and (ii) Geitonogamy (ii) Entomophily (Insect) one remains functional. The nucleus of functional cell further divides by mitosis without the cell wall (iii) Xenogamy (iii) Hydrophily (Water) formation upto eight nuclei. After rearrangement of nuclei, cell wall formation takes place leading to the Double Fertilization formation of female gametophyte or embryo sac. • Syngamy (generative) Three cells moves toward chalazal end and are called • PEN • PEC antipodals. One of the cell at micopylar end becomes egg and two become synergids. Two nuclei remain in Seed Special Modes of Post Fertilization Events the central cell and are called as polar nuclei. A Megaspore Mother Cell Dispersal Reproduction • Endosperm • Wind • Embryo • Such development from one functional cell is called • Embryo sac is thus 7-celled and 8-nucleate • Water • Apomixis (i) Monocot, (ii) Dicot monosporic development of embryo sac. structure. • Insect • Parthenocarpy • Seed and Fruit Formation • Polyembryony (i) True Fruits, (ii) False Fruits Topic 1. Flower Topic 3. Pollination Pollination: Transfer Parts of a Flower of pollen grains on stigma from anther Calyx Corolla Autogamy: Pollen grains G e i t o n o g a m y : P o l l e n Xenogamy: Pollen grains (Sepals) (Petals) land on the stigma of the grains land on the stigma land on the stigma of a same flower of different flower but of flower of different plant. the same plant. Androecium Gynoecium L. S. of a flower Self pollinating flowers are of two types: Outbreeding Devices (Stamen) (Pistil) Repeated self pollination can lead to reduced fitness • In Chasmogamous flowers, the pollination takes in plants called inbreeding depression. Adaptation 11 place in open flowers whereas in Cleistogamous of flowers to discourage self pollination is called flower, the pollination takes place in closed flowers, outbreeding devices, e.g. unisexual flowers, maturation ✎ Each chapter is divided into topics and which ensures seed setup, e.g. Viola, groundnut, time of stigma and pollens are different, pollens are self pea, Oxalis and Commelina, which ensures seed incompatible, position of anther and stigma is different. each concept is dealt separately. formation. Pollen-Pistil Interaction D:\\EG_Biology-12\\Open_Files\\Ch-6\\Ch-6 Agents of Pollination: Only a compatible pollen grain is allowed to germinate on stigma. This is due to proteins and chemicals present ✎ Flowchart representation of the chapter.\\06-Aug-2022  Ved_Goswamai   Proof-3 Air, water and insects aid pollination and thus are on stigma. This is called pollen-pistil interaction. Reader’s Sign _______________________ Date __________ called pollinating agents. Flowers are adapted to Compatible pollens absorb nutrients and water, pollen different types of pollinating agents. tube grows through the style and carries male gametes EXERCISE to embryo sac. • Anemophily (Wind pollination): Flowers are mostly I. Multiple Choice Questions 10. Viviparity is considered to be more evolved unisexual, dull coloured and are present in compact Artificial hybridisation 1. Which of the following is used as an atmospheric because: inflorescence; pollen grains are light, non-sticky, It is done by the following steps: pollution indicator? produced in large number; stigma is feathery with Emasculation: removal of anthers in bud condition, (a) the young ones are left on their own no nectar or scent. Bagging: protecting stigma from unwanted pollen (a) Lepidoptera (b) Lichens grains by covering them with paper bag, (b) the young ones are protected by a thick shell • Entomophily (Insect pollination): Flowers are Artificial pollination: dusting of selected pollen (c) Lycopersicon (d) Lycopodium bisexual, brightly coloured with nectar and scent to grains on stigma, (c) the young ones are protected inside the attract insects; pollens are sticky; anthers mostly Rebagging: prevents unwanted pollens and ensures 2. The theory of spontaneous generation stated that: mother’s body and are looked after they are mature earlier than stigma. germination of desired pollens. (a) life arose from living forms only. born leading to more chances of survival Tagging: writing information of hybridization on a • Hydrophily (Water pollination): Flowers are small, paper tied to a plant. (b) life can arise from both living and non-living. (d) the embryo takes a long time to develop inconspicuous, without nectar and scent; pollen grains are ribbon like mucilaginous; stigma cannot get wet but is sticky in nature. (c) life can arise from non-living things only. 11. Fossils are generally found in: ✎ All concepts are presented in points, whichSexual RepRoduction in FloweRing plantS 13 can be easily learnt and remember. (d) life arises spontaneously, neither from living (a) Sedimentary rocks nor from the non-living. ✎ Each concept is well explain by relevant (b) Igneous rocks diagrams, tables and illustrations for better 3. A n i m a l h u s b a n d r y a n d p l a n t b r e e d i n g understanding. programmes are the examples of: (c) Metamorphic rocks (a) reverse evolution (b) artificial selection (d) Any type of rock (c) mutation (d) natural selection 12. For the MN-blood group system, the frequencies of M and N alleles are 0.7 and 0.3, respectively. 4. Palaentological evidences for evolution refer to The expected frequency of MN-blood group the: bearing organisms is likely to be (a) development of embryo (a) 42% (b) 49% (c) 9% (d) 58% (b) homologous organs (c) fossils 13. Which type of selection is industrial melanism observed in moth, Biston bitularia: (d) analogous organs. 5. The bones of forelimbs of whale, bat, cheetah and (a) Stabilising (b) Directional man are similar in structure, because: (c) Disruptive (d) Artificial (a) one organism has given rise to another 14. The most accepted line of descent in human evolution is: (b) they share a common ancestor (c) they perform the same function (a) Australopithecus → Ramapithecus → Homo sapiens → Homo habilis (d) they have biochemical similarities (b) Homo erectus → Homo habilis → Homo 6. Analogous organs arise due to: sapiens (a) divergent evolution (b) artificial selection (c) Ramapithecus → Homo habilis → Homo erectus → Homo sapiens (c) genetic drift (d) Australopithecus → Ramapithecus → Homo (d) convergent evolution erectus → Homo habilis → Homo sapiens. 7. (p + q)2 = p2 + 2pq + q2 = 1 represents an equation 15. Which of the following is an example for link used in: species? (a) population genetics ✎ Exercise is segregated according to different variety of objective and subjective questions. (b) mendelian genetics (a) Lobe fish (b) Dodo bird Also includes previous year board questions and HOTS questions. (c) biometrics (c) Sea weed (d) Chimpanzee  (d) molecular genetics II. Fill in the blanks 8. Appearance of antibiotic-resistant bacteria is an 1. The first mammals were like _____ . example of: 2. ____ religious tells us about the theory of special (a) adaptive radiation creation. (b) transduction 3. Charles Darwin made a voyage around the world in a ship called ___ . (c) pre-existing variation in the population (d) divergent evolution 4. ____ is an extinct organism. 5. ____ indicates common ancestry. 9. Evolution of life shows that life forms had a trend of moving from: 1 Mark Questions (a) land to water 1. Write the similarity between the wing of a butterfly and the wing of a bat. What do you (b) dryland to wet land infer from the above with reference to evolution? [Delhi 2012] (c) fresh water to sea water (d) water to land Evolution 167 (viii)

D:\\EG_Biology-12\\Open_Files\\Ch-3\\Ch-3 Reader’s Sign _______________________ Date __________ \\ 06-Aug-2022  Ved_Goswami   Proof-3 Case Based Questions 1. Over population causes number of family (b) Cu ions make cervix hostile to the sperms. problems. Strategies like birth control methods help to control population explosion. Natural (c) Cu ions suppress sperms motility. methods of birth control do not involve (d) Cu ions inhibit ovulation. medications or devices to prevent pregnancy (ii) Which of the following IUDs makes uterus unsuitable for implantation? but rather rely on behavioural practices and/or making observations about menstrual cycle. (a) LNG-20 (b) Multiload 375 (i) Which method helps in contraception by (c) Cu7 (d) Lippes loop temporary absence of sex? (iii) Identify the correct statement for IUDs. (a) Coitus interruptus (a) They slowly release synthetic progesterone in the body. (b) Withdrawal method (b) They increase phagocytosis of sperms (c) Rhythm method within the uterus. (d) Lactational amenorrhea method (c) They block entry of sperms through the (ii) Assertion: The effectiveness of coitus cervix. interruptus method is limited. Reason: Some sperms may pass into vagina (d) Both (b) and (c). before ejaculation. (iv) Select the correct matched pair. (a) Both assertion and reason are true and reason is the correct explanation of (a) Hormone releasing IUD – LNG-20 assertion. (b) Non-medicated IUD – Progestasert (b) Both assertion and reason are true but (c) Copper releasing IUD – Lippes loop reason is not the correct explanation of (d) None of these. assertion. (v) Assertion: IUDs can cause excess menstrual bleeding and pain. (c) Assertion is true but reason is false. Reason: IUDs can perforate uterus. (d) Both assertion and reason are false. (a) Both assertion and reason are true and ✎ C a s e B a s e d Q u e s t i o n s a r e (iii) Why is lactational amenorrhea effective for reason is the correct explanation of about 4-5 months after parturition? assertion. included in each chapter. (a) Ovulation occurs on about the 14th day (b) Both assertion and reason are true but of menstruation. (b) Ovulation does not occur during intense reason is not the correct explanation of lactation. assertion. (c) This method inhibits mobility of sperms. (c) Assertion is true but reason is false. (d) Both (b) and (c). (d) Both assertion and reason are false. (iv) Which fact is not the basis of periodic absence 3. A young couple married for 5 years is unable method of birth control? to bear a child inspite of not practicing any (a) Ovum remains alive for about 1-2 days. birth control method. Upon consultation, doctor (b) Ovulation occurs on about 14th day of advised them an assisted reproductive technology menstruation. involving transfer of gametes into oviducts. (c) Sperms survive for about 3 days. (i) Identify the technique adopted by the couple. (d) Alteration in uterine endometrium. (a) ZIFT (b) IUI (v) On which days of menstrual cycle should coitus be avoided to prevent fertilisation? (c) GIFT (d) ICSI (a) 10-17 (b) 6-13 (ii) What is the pre-requisite of this technique? (c) 1-5 (d) 15-28 (a) Gamete formation should be normal. 2. Intrauterine devices are most widely accepted (b) Fallopian tubes should be normal. methods of contraception. These are used by (c) Female should have thick endometrial lining. females and are inserted by doctor or nurses in the uterus through vagina. However, these (d) Male should be able to copulate the female. devices are not recommended for those eventually intend to conceive. (iii) Assertion: GIFT is an in-vitro fertilisation technique. (i) How does CuT prevent conception? Reason: In GIFT, gametes are fertilised (a) Cu ions make uterus unsuitable for outside the female body. D:\\EG_Biology-12\\Open_Files\\Sample Paper_1 (Solved)\\Sample Paper_1 (Solved) implantation. \\ 06-Aug-2022  Ved_Goswami   Proof-3 Reader’s Sign _______________________ Date __________ RepRoductive HealtH 75 1Sample paper– (Solved) Time Allowed: 3 hours Maximum Marks: 70 General Instructions: (i) All questions are compulsory. (ii) This question paper has four sections: Section A, Section B, Section C and Section D. There are 33 questions in the question paper. (iii) Section–A has 14 questions of 1 mark each and 02 case-based questions. Section–B has 9 questions of 2 marks each. Section–C has 5 questions of 3 marks each and Section–D has 3 questions of 5 marks each. (iv) There is no overall choice. However, internal choices have been provided in some questions. A student has to attempt only one of the alternatives in such questions. (v) Wherever necessary, neat and properly labeled diagrams should be drawn. Section-A All questions are compulsory. In case of internal choices, attempt any one of them. I. Objective Type Questions (1 Mark) Q1. Which of the following is used as an atmospheric pollution indicator? 1 (a) Lepidoptera (b) Lichens (c) Lycopersicon (d) Lycopodium Ans. (b) Q2. Palaentological evidences for evolution refer to the: 1 (a) development of embryo (b) homologous organs (c) fossils (d) analogous organs. Ans. (c) Q3. Decomposers like fungi and bacteria are: 1 (i) autotrophs (ii) heterotrophs (iii) saprotrophs (iv) chemo-autotrophs. Choose the correct answer: ✎ Solved and unsolved sample 1 papers are included for mock test. (a) (i) and (iii), (b) (i) and (iv) (c) (ii) and (iii), (d) (i) and (ii) (a) development of embryo (b) homologous organs (c) fossils (d) analogous organs. Ans. (c) Q4. An inverted pyramid of biomass can be found in which ecosystem? (a) Forest (b) Marine (c) Grassland (d) Tundra Ans. (b) II. Very Short Answer Type Questions (1 Mark) Q5. Some allergens trigger sneezing and wheezing in human beings. What causes this type of response by the body? 1 Ans. Body produces IgE antibodies on exposure to allergens and release of chemicals like histamine and serotonin from the mast cells. Q6. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in plants? 1 Ans. Homozygus plants which are obtained after self pollination. Q7. What makes the Nucleopolyhedrovirus a desirable biological control agent? 1 Ans. These are species specific, narrow spectrum insectcides and do not harm non-target organisms. Q8. How is Agrobacterium tumifaciens able to transform a normal plant cell into a tumor? 1 Ans. Plasmid of Agrobacterium tumifaciens carries the genes for tumour, ‘Ti’. Agrobacterium transfers these cancer causing genes in plants thus causing tumour. Q9. Why is it essential to have a selectable marker in a cloning vector? 1 Ans. A selectable marker helps us to distinguish between transformed and non-transformed cells. Q10. Why do children cured by enzyme replacement therapy for adenosine deaminase deficiency need periodic treatment? 1 313 (ix)

CONTENTS 1. Sexual Reproduction in Flowering Plants...........................................................................................................11 2. Human Reproduction......................................................................................................................................... 40 3. Reproductive Health.......................................................................................................................................... 65 4. Principles of Inheritance and Variation.............................................................................................................. 79 5. Molecular Basis of Inheritance........................................................................................................................ 120 6. Evolution.......................................................................................................................................................... 161 7. Human Health and Diseases............................................................................................................................ 182 8. Microbes in Human Welfare............................................................................................................................ 209 9. Biotechnology: Principles and Processes......................................................................................................... 224 10. Biotechnology and its Application................................................................................................................... 250 11. Organisms and Populations.............................................................................................................................. 268 12. Ecosystem........................................................................................................................................................ 283 13. Biodiversity and its Conservation.................................................................................................................... 296 • Sample Paper-1 (Solved).................................................................................................................................. 313 • Sample Paper-2 (Unsolved)............................................................................................................................. 320 • Sample Paper-3 (Unsolved)............................................................................................................................. 325 (x)

1 Sexual Reproduction in Flowering Plants Topics overed   C 1.1 Flower 1.2 Pre-Fertilization Events 1.3 Pollination 1.4 Double Fertilization 1.5 Seeds and Fruits C hapter map SEXUAL REPRODUCTION IN FLOWERING PLANTS Flower Structure Male and Female Structure Outbreeding • Calyx • Stamen • Pistil Devices • Corolla (i) Filament (i) Stigma • Androecium (ii) Anther (ii) Style • Inbreeding • Gynoecium (iii) Ovary depression Pollen — Pistil Pollination Interaction • Type • Agencies • Compatible Pollen and (i) Autogamy (i) Anemophily (Wind) Stigma (ii) Geitonogamy (ii) Entomophily (Insect) (iii) Xenogamy (iii) Hydrophily (Water) Double Fertilization • Syngamy (generative) • PEN • PEC Seed Special Modes of Post Fertilization Events Dispersal Reproduction • Endosperm • Wind • Embryo • Water • Apomixis (i) Monocot, (ii) Dicot • Insect • Parthenocarpy • Seed and Fruit Formation • Polyembryony (i) True Fruits, (ii) False Fruits Topic 1. Flower Parts of a Flower Calyx Corolla (Sepals) (Petals) Androecium Gynoecium L. S. of a flower (Stamen) (Pistil) 11

Sexual reproduction in flowering plants Pre-fertilization Fertilization Post-fertilization events events Topic 2. Pre-fertilization Events Pollen grain: • In this differentiation of male and female • Each pollen grain is covered by inner (intine) and reproductive structures takes place. outer (exine) wall. Intine is made up of pectin and cellulose whereas exine is made of a resistant Male Reproductive Structures: Stamen, organic matter called sporopollenin Microsporangium, Pollen Grain • Locations where exine is absent are called germ Stamen pores from where pollen tube grows when it falls on stigma. Filament: Anther: Bilobed structure Slender stalk on the terminal end • Some people are allergic to pollen grains and suffer from bronchial disorders which leads to asthma or Anther is a bilobed and dithecous because it has two bronchitis. lobes and each lobe has two cavities. • Pollens are also considered to be nutrient rich and • Line of dehiscence opens up to release pollen grains are used as supplements to enhance the performance when anther is mature. of horses and athletes. • The section of anther shows a four sided (tetragonal) • Pollens lose their viability from minutes to few structure, with four microsporangia at each corner. hours or months depending upon variety of plants, e.g. Pollens of rice and wheat are viable only for 30 • Microsporangia develops into pollen sac which minutes whereas those of rosaceae, leguminoseae in turn contains sporogenous tissue. Each cell of and solanaceae family remain viable for months. sporogenous tissue develops into four pollen grains. The viability of pollens can be increased by cryopreservation technique in which they are stored • Each microsporangium has four walls: at very low temperature of –196°C in liquid nitrogen. (i) Epidermis (ii) Middle layer Female Reproductive Structure: Pistil (iii) Endothecium (iv) Tapetum Pistil • Epidermis, endothecium and middle layers are Stigma Style Ovary protective in nature whereas tapetum provides Pollen grains Connecting Basal part nutrition to developing pollen grains. Each cell has containing more than one nucleus and dense cytoplasm. land part of on stigma stigma and ovules Microsporogenesis: ovary • Development of pollen grains from sporogenous tissue. Ovule (Megasporangium) • Each cell of sporogenous tissue (microspore mother • Each ovary contains one or many ovules within a cell) divides by meiosis to become four haploid cells cavity called locule. called pollen tetrad or microspores. • Each ovule is attached to placenta by funicle. The Further development of a pollen grain attachment point is called hilum. Ovule is protected by inner and outer integuments. At micropyle, the • Each microspore divides unequally and forms two integuments are absent. Pollen tube enters via cells, larger one is vegetative cell and smaller one micropyle. is generative cell. • Nucellus is a nutritive tissue present in ovule for • Generative cell becomes spindle shaped and floats developing embryo sac or female gametophyte. in the cytoplasm of vegetative cell. • Generative cell further divides by mitosis and forms two male gametes. 12 Biology–12

Development of an embryo sac A Megaspore Mother Cell (Megasporogenesis) • Embryo sac is thus 7-celled and 8-nucleate • A cell differentiates and becomes a megaspore structure. mother cell. Megaspore mother cell divides by meiosis to form tetrad. Three cells degenerate and one remains functional. The nucleus of functional cell further divides by mitosis without the cell wall formation upto eight nuclei. After rearrangement of nuclei, cell wall formation takes place leading to the formation of female gametophyte or embryo sac. Three cells moves toward chalazal end and are called antipodals. One of the cell at micopylar end becomes egg and two become synergids. Two nuclei remain in the central cell and are called as polar nuclei. • Such development from one functional cell is called monosporic development of embryo sac. Topic 3. Pollination Pollination: Transfer of pollen grains on stigma from anther Autogamy: Pollen grains Geitonogamy:Pollen Xenogamy: Pollen grains land on the stigma of the grains land on the stigma land on the stigma of a same flower of different flower but of flower of different plant. the same plant. Self pollinating flowers are of two types: Outbreeding Devices Repeated self pollination can lead to reduced fitness • In Chasmogamous flowers, the pollination takes in plants called inbreeding depression. Adaptation place in open flowers whereas in Cleistogamous of flowers to discourage self pollination is called flower, the pollination takes place in closed flowers, outbreeding devices, e.g. unisexual flowers, maturation which ensures seed setup, e.g. Viola, groundnut, time of stigma and pollens are different, pollens are self pea, Oxalis and Commelina, which ensures seed incompatible, position of anther and stigma is different. formation. Pollen-Pistil Interaction Agents of Pollination: Only a compatible pollen grain is allowed to germinate on stigma. This is due to proteins and chemicals present Air, water and insects aid pollination and thus are on stigma. This is called pollen-pistil interaction. called pollinating agents. Flowers are adapted to Compatible pollens absorb nutrients and water, pollen different types of pollinating agents. tube grows through the style and carries male gametes to embryo sac. • Anemophily (Wind pollination): Flowers are mostly unisexual, dull coloured and are present in compact Artificial hybridisation inflorescence; pollen grains are light, non-sticky, It is done by the following steps: produced in large number; stigma is feathery with Emasculation: removal of anthers in bud condition, no nectar or scent. Bagging: protecting stigma from unwanted pollen grains by covering them with paper bag, • Entomophily (Insect pollination): Flowers are Artificial pollination: dusting of selected pollen bisexual, brightly coloured with nectar and scent to grains on stigma, attract insects; pollens are sticky; anthers mostly Rebagging: prevents unwanted pollens and ensures mature earlier than stigma. germination of desired pollens. Tagging: writing information of hybridization on a • Hydrophily (Water pollination): Flowers are small, paper tied to a plant. inconspicuous, without nectar and scent; pollen grains are ribbon like mucilaginous; stigma cannot get wet but is sticky in nature. Sexual Reproduction in Flowering Plants  13

Topic 4. Double Fertilization either consumed by developing embryo or remains in the seeds. • When two male gametes are released in the synergid by a pollen tube, out of the two male gametes, one Embryo: Zygote divides by mitosis into two cells fuses with egg cell and other fuses with two polar arranged in linear fashion, upper is called basal cell nuclei, which is called double fertilization. and the lower one is called terminal cell. Terminal cell further divides by mitosis and undergoes various • Fusion with egg cell gives rise to zygote and with two stages viz. pro-embryo, globular and heart shaped, polar nuclei gives rise to primary endospermic before developing into mature embryo. nucleus (PEN). Structure of a dicot embryo: Two cotyledons Post-fertilization Events attached to embryonic axis. Distal plumule, lateral cotyledons present, coleoptiles and coleorhiza absent. Following double fertilization events of endosperm, Radicle give rise to root and plumule give rise to shoot. embryo development, maturation of ovule(s) into Root is covered by a root tip. seed(s) and ovary into fruit are collectively termed as post-fertilization events. Structure of a monocot embryo: One cotyledon attached to embryonic axis. It is called scutellum. Endosperm: PEN develops into endosperm. It Lateral plumule and terminal cotyledon present, provides nutrition to developing embryo. During coleoptiles protect plumule and coleorrhiza protects development of endosperm, free nuclear division takes the radicle. place and cell wall is formed later. Endosperm can be Topic 5. Seeds and Fruits Seed and Fruit Formation: Different parts of ovule after Apomixis: Development of seed without fertilization. fertilization develop into the following parts: There is no segregation in such seeds, so that are used to make hybrid seeds, which reduces the cost of • Ovule → seed production. • Ovary → fruit Polyembryony: Two or more embryos are present in a seed. Such embryos develop with mitosis, thus are • Ovary wall → pericarp or fruit wall genetically same as their parents, e.g. citrus plants. • Integuments → seed coat, outer- testa and Fruits: If fruit develops from ovary then it is true fruit, e.g. inner–tegmen. pea, maize, mango, banana, tomato etc. If fruit develops from any part of the flower other than ovary then it is • Nucellus if persistent → perisperm false fruit, e.g. apple, peach, strawberry, pear etc. Types of seeds: Albuminous: Residual endosperm Role of Fruits: Protects and aids dispersal of seeds. present, e.g. wheat, maize, rice, castor etc. Non- Provides nutrition. Acts as a source of food. Stores many albuminous: Endosperm fully consumed by sugars, proteins, oils, organic acids and other nutrients. cotyledons, e.g. pea, groundnut etc. Parthenocarpy: Fruits develop without fertilization and are seedless, e.g. banana, grapes. Role of Seeds in Plant Life: Seeds help in Dispersal, Provide nourishment to seedlings, Protect embryo, Significance of Seed Dispersal Give rise to variation. • Survival of the plant species Dormancy and seed storage: Metabolic inactive stage of seed is called dormancy. Viable dehydrated seeds • To avoid competition among the plants for resources are dormant. Viability varies from few to thousands of spread in wide area. years, e.g. viability of Lupinus arcticus is found to be more than 10,000 years and that of Phoenix dactylifera is 2000 years. EXERCISE I. Multiple Choice Questions are: (ii) Carpel 1. Among the terms listed below, those that of are (iv) Sepal (i) Androecium not technically correct names for a floral whorl (iii) Corolla 14 Biology–12

(a) (i) and (iv) (b) (iii) and (iv) (iv) It has an egg apparatus situated at the chalazal end (c) (ii) and (iv) (d) (i) and (ii) (a) (i) and (iv) (b) (ii) and (iii) 2. Embryo sac is to ovule as _______ is to an anther. (a) Stamen (b) Filament (c) (i) & (ii) (d) (ii) & (iv) (c) Pollen grain (d) Androecium 10. Autogamy can occur in a chasmogamous flower if: 3. In a typical complete, bisexual and hypogynous flower the arrangement of floral whorls on the (a) Pollen matures before maturity of ovule thalamus from the outermost to the innermost is: (b) Ovules mature before maturity of pollen (a) Calyx, corolla, androecium and gynoecium (c) Both pollen and ovules mature simultaneously (b) Calyx, corolla, gynoecium and androecium (d) Both anther and stigma are of equal lengths. (c) Gynoecium, androecium, corolla and calyx 11. Choose the correct statement from the following: (d) Androecium, gynoecium, corolla and calyx (a) Cleistogamous flowers always exhibit 4. A dicotyledonous plant bears flowers but never autogamy produces fruits and seeds. The most probable (b) Chasmogamous flowers always exhibit cause for the above situation is: geitonogamy (a) Plant is dioecious and bears only pistillate (c) Cleistogamous flowers exhibit both autogamy flowers and geitonogamy (b) Plant is dioecious and bears both pistillate (d) Chasmogamous flowers never exhibit and staminate flowers autogamy (c) Plant is monoecious 12. A particular species of plant produces light, non- sticky pollen in large numbers and its stigmas are (d) Plant is dioecious and bears only staminate flowers. long and feathery. These modifications facilitate 5. The outermost and innermost wall layers of pollination by: microsporangium in an anther are respectively: (a) Insects (b) Water (a) Endothecium and tapetum (c) Wind (d) Animals. (b) Epidermis and endodermis 13. From among the situations given below, choose the one that prevents both autogamy and (c) Epidermis and middle layer geitonogamy. (d) Epidermis and tapetum (a) Monoecious plant bearing unisexual flowers 6. During microsporogenesis, meiosis occurs in: (b) Dioecious plant bearing only male or female (a) Endothecium flowers (b) Microspore mother cells (c) Monoecious plant with bisexual flowers (c) Microspore tetrads (d) Dioecious plant with bisexual flowers (d) Pollen grains. 14. In a fertilised embryo sac, the haploid, diploid and triploid structures are: 7. From among the sets of terms given below, identify those that are associated with the (a) Synergid, zygote and primary endosperm gynoecium. nucleus (a) Stigma, ovule, embryo sac, placenta (b) Synergid, antipodal and polar nuclei (b) Thalamus, pistil, style, ovule (c) Antipodal, synergid and primary endosperm (c) Ovule, ovary, embryo sac, tapetum nucleus (d) Ovule, stamen, ovary, embryo sac (d) Synergid, polar nuclei and zygote. 8. Starting from the innermost part, the correct 15. In an embryo sac, the cells that degenerate after sequence of parts in an ovule are, fertilisation are: (a) egg, nucellus, embryo sac, integument (a) Synergids and primary endosperm cell (b) egg, embryo sac, nucellus, integument (b) Synergids and antipodals (c) embryo sac, nucellus, integument, egg (c) Antipodals and primary endosperm cell (d) egg, integument, embryo sac, nucellus. (d) Egg and antipodals. 9. From the statements given below choose 16. The hilum in a typical angiospermic ovule the option that are true for a typical female represents the junction between gametophyte of a flowering plant: (a) Integuments and embryo sac. (i) It is 8-nucleate and 7-celled at maturity (b) Embryo sac and the nucellus. (ii) It is free-nuclear during the development (c) Body of the ovule and the funicle. (iii) It is situated inside the integument but outside the nucellus (d) Nucellus and the funicle [CBSE 2022] Sexual Reproduction in Flowering Plants  15

17. The term used for the embryo entering into the 3. Syngamy means fusion of gametes. state of inactivity as the seed mature is– 4. In plants, meiosis occurs in pollen grain. 5. Only meiotic divisions are involved in asexual (a) Quiescent (b) Parthenogenesis (c) Parthenocarpy (d) Doremancy reproduction. [CBSE 2022] 6. Within each ovule a haploid embryo sac usually 18. The ploidy of the apomictic embryo developed from the integument cells and megaspore mother containing 7 nuclei is formed. cell without reduction division respectively will 7. Cross-pollination requires abiotic or biotic agent. be- 8. A population of genetically identical plants (a) 2n and 2n (b) n and n derived from an individual is called a seed. (c) 2n and n (d) 3n and 2n 9. A clone is a group of individual obtained through [CBSE 2022] 19. An undifferentiated sheath covering the root cap vegetative propagation. of a monocotyledonous embryo is IV. M atch the items of Column I with those of Column II (a) Scutellum (b) Coleorhiza Column I Column II (c) Coleoptile (d) Epiblast (i) Parthenocarpy (a) Tepal [CBSE 2022] (ii) Tissue culture (b) Edible banana 20. Residual persistent nucellus in black pepper is known as (iii) Perianth (c) Scion (iv) Grafting (d) Ground nut (a) Perisperm (b) Pericarp (c) Pulvinus (d) Perianth (v) Non-endospermous (e) Callus [CBSE 2022] seed 21. Amongst the insects the dominant biotic 1 Mark Questions pollinating agents are– 1. An anther with malfunctioning tapetum often (a) Ants (b) Wasps fails to produce viable male gametophytes. Give (c) Beetles (d) Bees [CBSE 2022] any one reason.[Delhi 2010/2013] 22. A genetic mechanism which prevents inbreeding 2. How do the pollen grains of Vallisneria protect themselves?[All India 2012] depression in majority of angiospermic plants is 3. Write the function of coleoptiles. [Delhi 2012] (a) Parthenogenesis 4. Write the function of scutellum. [Delhi 2012] (b) Parthenocarpy (c) Mutation 5. Normally one embryo develops in one seed but when an orange seed is squeezed many embryos (d) Self-incompatability [CBSE 2022] of different shapes and sizes are seen. Mention II. Fill in the Blanks how it has happened? [All India 2010, Delhi 2011] 1. Inside ovary, ovules develop from a special tissue 6. Name the part of the flower which the tassels of called ______ . the corn cob represent. [All India 2014] 2. Each microspore mother cell has ____________ of 7. What is pollen-pistil interaction and how is it chromosomes and therefore is _______ . mediated?[Foreign 2014] 3. Stem cuttings are frequently used for _____ . 8. State the function of filiform apparatus found in 4. Mustard and tomato are examples of _____ flower. mature embryo sac of an angiosperm. 5. Spike with unisexual flowers is called ______ . 6. Bryophyllum is the best example of propagation [Foreign 2014] by ______ . 9. Differentiate between xenogamy and geitonogamy. 7. Fertilization in angiosperms is referred to as [All India 2014 C] _______ fertilization. 10. A bilobed, dithecous anther has 100 micro-spore 8. In Calotropis, all the microspores of anther lobe mother cell per micro-sporangium. How many male gametophytes this anther can produce? remain united to form ____ . [Delhi 2010] 9. Albuminous seeds store reserve food material in 11. Why do the pollen grains of Vallisneria have a ______ . mucilaginous covering? [Delhi 2010 C] 10. The ______ direct the growth of pollen tube 12. Give an example of a plant which came into India towards egg apparatus by secreting some as a contaminant and is a cause of pollen allergy. chemical substances. [All India 2014] III. True or False 13. Write the function of tapetum in anthers. 1. Coleoptile is the sheath covering of plumule. [Delhi 2012] 2. In Vallisneria the male flowers are released in 14. Explain the function of germ pores. air. [AlI India 2012] 16 Biology–12

15. Write the characteristic features of anemophilous 33. Name the part of flower that contributes to fruit flowers.  [All India 2012 C] formation in strawberry and guava respectively. 16. The reason why anthers of angiosperm flowers [All India 2009 C] are described as dithecous. [Delhi 2011] 34. Strawberry is sweet and eaten raw just like any 17. Mention any one application of a pollen bank. other fruit. Why do botanists call it a false fruit? [Delhi 2011 C] [All India 2008 C] 18. All papaya plants bear flowers but fruits are seen 35. Hybrid seeds have to be produced year after year. Give reason. [Delhi 2011] in some. Explain.  [All India 2011 C] 19. Write the characteristic features of anther, pollen 36. What is apomixis? What is its importance? and stigma of wind pollinated flowers. [All India 2008 C, Delhi 2011 C] [Delhi 2010] 37. Mention the pollinating agent of an inflorescence of small dull-coloured flowers with well-exposed 20. The microscopic pollen grains of the past are obtained as fossils. Mention the characteristic of stamens and large feathery stigma. Give any one the pollen grains that makes it happen. characteristic of pollen grains produced by such [Delhi 2009] flowers.[Delhi 2009] 21. Name the type of flower which favours cross 38. Mention advantage of apomictic seeds to farmers. [All India 2014] pollination.  [All India 2009] 39. Name the type of pollination as a result of which 22. Why is bagging of the emasculated flowers genetically different types of pollen grains of the essential during hybridisation experiment? same species land on the stigma.[Foreign 2009] [All India 2009] 2 Marks Questions 23. The following statements (a), (b) and (c) seem to describe the water-pollinated submerged plants. 40. Name the organic materials of which the exine Which one of these statements is incorrect? and intine of an angiosperm pollen grains are made up of. Explain the role of exine. (a) The flowers do not produce nectar. (b) The pollen grains have mucilaginous covering. [Delhi 2014] (c) The brightly coloured female flowers have 41. Draw a diagram of a matured microspore of an long stalk to reach the surface.[Foreign 2009] angiosperm. Label its cellular components only. 24. How can pollen grains of wheat and rice which [Foreign 2014] tend to lose viability within 30 minutes of their 42. Name all the haploid cells present in an release be made available months later for unfertilised mature embryo-sac of a flowering breeding programmes? [Delhi 2009 C] plant. Write the total number of cells in it. 25. Mention one application of pollen bank. How are [All India 2013] pollens stored in a bank? [Delhi 2008 C] 43. Differentiate between the two cells enclosed in a 26. Mention the exact location or the site in a mature male gametophyte of an angiosperm. flowering plant where the following developments [All India 2013] take place. 44. Draw labelled diagram of a mature ovule and (a) Triple fusion embryo sac with its contents. [Delhi 2013 C] (b) Release of male gametes [All India 2011 C] 45. In the T. S. of a mature anther given below, 27. What is double fertilisation? [Delhi 2009 C] identify 'a' and 'b' and mention their functions. 28. Mention the function of coleorhiza. [Foreign 2009] [All India 2012, Delhi 2015 C] 29. Why is banana referred to as a parthe-nocarpic fruit?[All India 2012, 2013 C] 30. The meiocyte of rice has 24 chromosomes. Write a the number of chromosomes in its endosperm. b [All India 2013 C, Foreign 2009 C] 46. Geitonogamous flowering plants are genetically autogamous but functionally cross-pollinated. 31. What is pericarp? Mention its function. Justify.[Delhi, 2013] [All India 2011 C] 47. Suggest two advantages to a farmer for using apomictic seeds of hybrid varieties.[Delhi 2015] 32. Name the mechanism responsible for the formation of seed without fertilisation in 48. Differentiate between albuminous and non- albuminous seeds, giving one example of each. angiosperms. Give an example of a species of [Delhi 2011] flowering plants with such seed formation. [Delhi 2010 C] Sexual Reproduction in Flowering Plants  17

49. Flower of brinjal is referred to as chasmogamous 67. Draw a diagram of a fertilised embryo sac of a while that of beans is cliestogamous. How are they dicot flower. Label all its cellular components. different from each other? [Delhi 2008] [Delhi 2015 C] 50. (a) Draw a schematic diagram of T. S. of a mature 68. (a) Mention any four strategies adopted by anther. Label only the layers that help in flowering plants to prevent selfpoll-ination. dehiscence of the anther to release pollen (b) Why is geitonogamy also referred to as grains. genetical autogamy? [Delhi 2010] (b) Why is exine of the pollen grain not a 69. Explain the process of artificial hybri-disation to continuous layer? [All India 2009 C] get improved crop variety in: 51. Banana crop is cultivated by farmers without (a) Plants bearing bisexual flowers sowing of seeds. Explain how the plant is (b) Female parent producing unisexual flowers. propagated.[Delhi 2014 C] [Delhi 2010] 52. Name the cell from which the endosperm of coconut develops. Give the characteristics of 70. How many haploid cells are present in mature female gametophyte of a flowering plant? Name endosperm of coconut. [Delhi 2009] them.[Delhi 2010] 53. Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from 71. Identify and label the parts in the given anatropous ovule. [All India 2010 C] each other with respect to seeds? [Delhi 2009] 54. List the different types of pollination depending A upon the source of pollen grain. [Delhi 2016] 55. A single pea plant in your kitchen garden produces B pods with viable seeds, but the individual papaya plant does not. Explain. [All India 2016] C D 56. Gynoecium of a flower may be apocarpous or syncarpous. Explain with the help of an example each.[All India 2016] 57. Why do hermaphrodite angiosperms develop 72. Explain how geitonogamy is functionally similar outbreeding devices? Explain any two such to cross pollination and genetically similar to devices with the help of examples. autogamy.[All India 2009 C] [All India 2015 C] 73. Draw the longitudinal section of pistil showing 58. Draw the labelled structure of mature embryo pollen tube. [All India 2009 C] sac.[Delhi 2007, All India 2013 C] 74. Cleistogamous flowers of Commelina are 59. List the adaptive features of water pollinated invariably autogamous. Mention its one advantage flowers like Vallisneria.[Delhi 2013 C] and one disadvantage to the plant. 60. State one advantage and one disadvantage of cleistogamy.[All India 2011 C, 2012] [All India 2009 C] 61. How does the study of different parts of a flower 75. Draw a diagrammatic sketch of the sectional view help in identifying wind as its pollinating agent? of a typical anatropous ovule. [Delhi 2008] [Delhi, All India 2012] 76. What is geitonogamy? Give its one similarity to 62. Trace pollen grain development from sporogenous (a) autogamy and (b) xenogamy tissue in the anther. [Delhi 2012 C] [Delhi 2008 C] 63. What is the role of endothecium and tapetum in an anther? [All India 2012 C] 77. Draw a diagram of L. S. of an anatropous ovule of an angiosperm and label the following parts: 64. Differentiate between autogamy, geitonogamy and xenogamy. [All India 2012 C] (a) Nucellus (b) Integument 65. Why does a breeder need to emasculate a bisexual (c) Antipodal cell (d) Secondary nucleus flower? Mention a condition in a flower where [Delhi 2007] emasculation is not necessary. 78. Draw a sectional view of a pollen grain and label the following parts: [Delhi 2011 C, 2009 C] (a) Intine 66. Explain why emasculation and bag-ging are practised during artificial hybridisation programme (b) Exine involving plants bearing bisexual flowers. (c) Germ pore [Delhi 2011 C] (d) Generative cell [Delhi 2007] 18 Biology–12

79. In the given figure of embryo sac, label the parts 95. (a) Given below is a T. S. of an apple. Identify A, (1), (2), (3) and (4). [All India 2010] B and C. 1 A C B 2 3 4 80. In angiosperms, zygote is diploid while primary Mesocarp endosperm cell is triploid. Explain. (b) Why is an apple categorised as a false fruit? [All India 2013] [Delhi 2010 C] 81. Explain triple fusion in angiosperm. 96. Draw a vertical section of a maize grain and [Delhi 2013 C] label (a) pericarp, (b) scutellum, (c) coleoptile and 82. Draw a labelled diagram of a male gametophyte of an angiosperm. Why does it possess two male (d) radicle. [All India 2009] gametes to fertilise one ovule? 97. Draw a labelled typical dicot embryo. [All India, Delhi 2013 C] [All India 2009] 83. Describe the process of syngamy and triple fusion 98. What do you technically call the water that you drink and the kernel that you eat in a tender in an angiosperm.  [Delhi 2011 C] coconut?[All India 2009 C] 84. Mention the reasons for difference in ploidy of zygote and primary endosperm nucleus in an 99. What is apomixis? How is the phenomenon useful to the farmer? [Foreign 2015] angiosperm.[Delhi 2010] 85. Draw a schematic labelled diagram of a fertilised 100. Explain the different ways apomictic seed can embryo sac of an angiosperm. [All India 2008] develop. Give an example of each. 86. Explain the process of double fertilisation in [All India 2014] angiosperms.[Delhi 2008 C] OR 87. Banana fruit is said to be parthenocarpic whereas How do plants produce seeds through apomixis? turkey is said to be parthe-nogenetic. Why? Explain with the help of an example. [Delhi 2015 C] [Delhi 2013 C] 88. Write the difference between the tender coconut 101. Why are some seeds of Citrus referred to as water and the thick white kernel of a mature polyembryonic? How are they formed? coconut and their ploidy. [All India 2015 C] [All India 2013 C] 89. Draw a labelled mature stage of a dicotyledonous 102. Fertilisation is essential for production of seed, embryo.[Delhi 2010 C, All India 2012 C, 2014] but in some angiosperms, seeds develop without 90. Some angiosperm seeds are said to be 'albuminous', fertilisation. whereas few others are said to have a perisperm. (a) Give an example of an angiosperm that Explain each with the help of an example. produces seeds without fertilisation. Name [Foreign 2014] the process. 91. Write the changes a fertilised ovule undergoes (b) Explain the two ways by which seeds develop within the ovary in an angiosperm plant. without fertilisation. [All India 2009] [All India 2013] 103. A pollen grain in angiosperm at the time of 92. (a) Describe the endosperm development in dehiscence from an anther could be 2-celled or coconut.[All India 2011 C] 3-celled. Explain. How are the cells placed within the pollen grain when shed at a 2-celled stage? (b) Why is tender coconut considered healthy  [All India 2017] source of nutrition? (c) How are pea seeds different from castor seeds 3 Marks Questions with respect to endosperm? [All India 2013] 104. Draw a diagram of a male gametophyte of 93. Write the fate of the products of triple fusion in an angiosperm. Label any four parts. Why is the mature fruit of coconut. [Delhi 2013 C] sporopollenin considered the most resistant 94. Draw a labelled diagram of the L. S. of a monocot seed (Maize grain). [All India 2013 C] organic material?  [Delhi 2011] Sexual Reproduction in Flowering Plants  19

105. Why are angiosperm anthers called dithecous? 120. Describe the process of megasporogenesis in Describe the structure of its microsporangium. angiosperms until 8 nucleate stage. [All India 2014] [All India 2013] 106. Where is sporopollenin present in plants? State 121. Describe the structure of a 3-celled pollen grain its significance with reference to its chemical of an angiosperm. [Delhi 2012 C] nature.[Delhi 2012] 122. Explain the processes of emasculation and bagging of flowers. State their importance in 107. How does cleistogamy ensure autogamy? breeding experiments. [Delhi 2012 C] [Delhi 2013] 123. Describe the development of a 7-celled female 108. Explain the steps involved in artificial pollination gametophyte from a megaspore mother cell in of autogamous flowers. [Delhi 2013] an angiosperm. [All India 2012 C] 109. Describe the development of endosperm after double fertilization in an angiosperm. Why does 124. Explain any three outbreeding devices in flowering plants. [All India 2012 C] endosperm development preceeds that of zygote? 125. Draw a diagram of a vertical section of an [Delhi 2015] anatropous ovule of an angiosperm. Label the 110. Explain any three advantages the seeds offer to following parts. angiosperms.[Delhi 2014] (a) Hilum (b) Micropyle 111. A non biology person is quite shocked to know that apple is a false fruit, mango is a true fruit (c) Outer integument (d) Nucellus and banana is a seedless fruit. As a biology (e) Embryo sac (f) Antipodals. student how would you satisfy this person? [All India 2011 C] [Delhi 2015] 126. (a) Mention the exact location or the site in a flowering plant where the following 112. Differentiate between perisperm and endosperm giving one example of each. [All India 2012] developments take place. 113. Draw a labelled sketch of a mature 7-celled, (i) Deposition of sporopollenin 8-nucleate embryo-sac. Which one of the cell in (ii) Megasporogenesis an embryo-sac produces endosperm after double (b) Draw a labelled diagram of a male gametophyte of an angiosperm. [All India 2011 C] fertilization?[Delhi 2013, Foreign 2016] 127. Draw a labelled L. S. of pistil showing path of 114. (a) Name the organic material exine of the pollen pollen tube entering the embryo sac. grain is made up of. How is this material [All India 2011 C] advantageous to pollen grain? 128. Explain the characteristic features of flowers that (b) Still it is observed that it does not form a facilitate wind-pollination. [Delhi 2011 C] continuous layer around the pollen grain. 129. Trace the development of megaspore mother cell Give reason. up to the formation of a mature embryo sac in a (c) How are 'pollen banks' useful? flowering plant. [Delhi 2010] [All India 2016] 130. Draw a longitudinal section of a postpollinated 115. (a) Make a list of any three outbreeding devices pistil showing entry of pollen tube into a mature that flowering plants have developed and embryo-sac. Label filiform apparatus, chalazal explain how they help to encourage cross- end, hilum, antipodals, male gametes and secondary nucleus. [Delhi 2010] pollination. 131. Given below is an enlarged view of one (b) Why are angiosperm anthers called dithecous? microsporangium of a mature anther. Describe the structure of its microsporangium. A [All India 2014] B 116. Draw L. S. of a pistil showing pollen tube entering Microspore mother cells the embryo-sac in an angiosperm and label any C six parts other than stigma, style and ovary. [All India 2013] 117. Explain the process of microsporogenesis in angiosperms. [Delhi 2013 C] (a) Name ‘A’, ‘B’ and ‘C’ wall layers. 118. Explain the process of megasporogenesis in angiosperms. [Delhi 2012] (b) Mention the characteristics and function of the cells forming wall layer ‘C’.[Delhi 2008 C] 119. Write the mode of pollination in Vallisneria and water lily. Explain the mechanism of pollination 132. State the significance of pollination. List any four differences between wind-pollinated and animal- in Vallisneria. [All India 2013 C] pollinated flowers. [Delhi 2008 C] 20 Biology–12

133. Enumerate any six adaptive floral characteristics 148. (a) Draw a labelled sectional view of an of a wind pollinated plant. [All India 2008 C] albuminous seed. 134. Draw a neat labelled sketch of L. S. of an (b) How are seeds advantageous to flowering endospermous monocot seed. [Delhi 2012 C] plants?[Delhi 2010] 135. Why is fertilisation in angiosperms re-ferred to 149. as double fertilisation? Explain. [All India 2013 C] 136. In an angiosperm, the embryo sac is haploid, zygote is diploid and endosperm is triploid. Justify giving reasons for each stage. [All India 2009 C] (a) Identify the figure. (b) Name the initial cell from which this structure 137. List the components of the embryo sac and mention their fate on fertilisation. [Delhi 2008] has developed. 138. Why does a pollen grain possess two male (c) Draw the next mature stage and label the gametes? Explain. [Delhi 2007] parts.[Foreign 2009] 139. Explain the development of a mature embryo 150. (a) Can a plant flowering in Mumbai be pollinated from the embryo sac of dicot flower. by pollen grains of the same species growing in New Delhi ? Provide explanations to your [Delhi 2011 C, 2015 C] answer. 140. List the post-fertilisation events in angiosperms. (b) Draw the diagram of a pistil where pollination [Delhi 2014 C] 141. Name the two end products of double fertilisation has successfully occurred. Label the parts in angiosperms. How are they formed? Write involved in reaching the male gametes to its their fate during the development of seed. desired destination. [All India 2017] [Delhi 2014 C] 151. Explain the process of pollination in Vallisneria. 142. H o w i s p a r t h e n o c a r p y d i f f e r e n t f r o m How is it different in water-lily, which is also an parthenogenesis? Give an example of each. aquatic plant? [All India 2017] [Delhi 2013 C] 152. How many cells are present in the pollen grains at the time of their release from anther? Name 143. L. S. of a maize grain is given below. Label the parts A, B, C and D in it. the cells. [All India 2017] 153. (a) Trace the development of an endosperm after fertilization with reference to coconut. A Mention the importance of endosperm development. C (b) Write the importance of 'pollen bank'. [All India 2017] B D [All India 2012] 5 Marks Questions 144. (a) Give one example each of albuminous and non 154. Draw a diagrammatic sectional view of a mature albuminous seeds. anatropous ovule and label the following parts in it: (b) Name the parts of the ovule and the embryo (a) that develops into seed coat. sac of an angiosperm that develop into: (b) that develops into an embryo after fertilization. (c) that develops into an endosperm in an (i) Perisperm, (ii) seed coats, albuminous seed. (iii) endosperm, (iv) embryonal axis. [Delhi 2012 C] (d) through which the pollen tube gains entry into the embryo sac. 145. Explain how false, true and partheno-carpic fruits are different from each other. Give one example of (e) that attaches the ovule to the placenta. each.[Delhi 2012 C] [Delhi 2013] 146. Draw a labelled diagram of L. S. of an embryo of grass (any six labels). [Delhi 2011] 155. (a) Draw a diagram of a mature embryo sac of an angiosperm and label the following parts in 147. Differentiate between the following giving one it: example of each: (i) Filiform apparatus (ii) Synergids (a) Parthenogenesis and Parthenocarpy (iii) Central cell (iv) Egg cell (b) Perisperm and Pericarp [Delhi 2011 C] (v) Polar nuclei (vi) Antipodals Sexual Reproduction in Flowering Plants  21

(b) Write the fate of egg cell and polar nuclei after (c) How many pollen grains must have minimally fertilization.[Delhi 2013] pollinated the carple? 156. Describe the characteristic features of wind (d) How many male gamets would have used to pollinated flowers.  [Delhi 2013] produce these 200 viable seeds? 157. Describe the characteristic features of an insect (e) How many megaspore mother cells were pollinated flower.  [Delhi 2013] required in this process? [Delhi 2015] 158. As a senior biology student you have been asked 166. Explain the post-pollination events leading to seed to demonstrate to the students of secondary level production in angiosperms. List the different in your school, the procedure(s) that shall ensure cross pollination in a hermaphrodite flower. List types of pollination depending upon the source of pollen grain. [Delhi 2016] the different steps that you would suggest and provide reasons for each one of them. 167. (a) Describe the formation of mature female gametophyte within an ovule in angiosperms. [All India 2016] (b) Describe the structure of the cell(s) that 159. Why does endosperm development precedes guide(s) the pollen tube to enter the embryo embryo development in angiosperm seeds? State sac.[All India 2014 C] the role of endosperm in mature albuminous seeds. Describe with the help of three labelled 168. (a) Draw a diagram of an enlarged view of T. S. diagrams the different embryonic stages that of one microsporangium of an angiosperm and label the following parts. include mature embryo of dicot plants. (i) Tapetum [Delhi 2014] (ii) Middle layer 160. Explain the phenomenon of double fertilization. Draw labelled diagram of a typical anatropous (iii) Endothecium ovule.  [Delhi 2014] (iv) Microspore mother cells 161. Double fertilization is reported in plants of both, (b) Mention the characteristic features and castor and groundnut. However the nature seeds function of tapetum. of groundnut are non-albuminous and castor are (c) Explain the following giving reasons: albuminous. Explain the post fertilization events (i) Pollen grains are well preserved as fossils. that are responsible for it.  [All India 2015] (ii) Pollen tablets are in use by people these days.[Foreign 2011] 162. Why is fertilization in angiosperm refer-red to as double fertilization? Mention the ploidy of the 169. How does the pollen mother cell develop into a cells involved. Draw a neat labelled sketch of L.S. mature pollen grain? Illustrate the stages with labelled diagrams. [Delhi 2009] of an endosperms monocot seed. [All India 2012] 170. Explain with the help of a diagram the 163. Explain the events upto fertilization that occur development of a mature embryo sac from a in a flower after the pollen grain has landed on its compatible stigma. [Foreign 2016] megaspore mother cell in angiosperm. 164. A flower of brinjal plant following the process of [Delhi 2009] sexual reproduction produces 360 viable seeds. 171. Draw a labelled diagram of an anther lobe at Answer the following questions giving reasons: microspore-mother cell stage. Mention the role of different wall layers of anther. [Delhi 2009C] (a) What is the minimum number of pollen grains that must have been involved in the 172. (a) Draw a labelled diagram of the sectional view pollination of its pistil? of a mature pollen grain in angiosperms. (b) What would have been the minimum number (b) Explain the functions of its different parts. of ovules present in the ovary? [Delhi 2008, 2014] (c) How many megaspore mother cells were 173. (a) Draw a labelled diagram of the sectional view involved? of microsporangium of angiosperm. (d) What is the minimum number of microspore (b) Explain the development of male gametophyte mother cells involved in the above case? in the microsporangium. [Delhi 2015 C] (e) How many male gametes were involved in 174. (a) Describe the sequence of the process of this case? [Delhi 2015] microsporogenesis in angiosperms. 165. A flower of tomato plant following the process of (b) Draw a labelled diagram of a two celled final sexual reproduction produces 200 viable seeds. structure formed.  [Delhi 2015 C] Answer the following questions giving reasons: 175. Angiosperm flowers may be monoecious, (a) What would have been the minimum number cleistogamous or show self incompatibility. Describe the characteristic features of each of ovules present in prepollinated pistil? one of them and state which one of these (b) How many microspore mother cells would flowers promotes inbreeding and outbreeding minimally be required to produce requisite number of pollen grains? respectively.[Delhi 2014 C] 22 Biology–12

176. (a) Draw a labelled schematic diagram of the (iv) What is the minimum number of microspore transverse section of a mature anther of an mother cells involved in the above case? angiosperm plant. (v) How many male gametes were involved in this case? [Delhi 2015] (b) Describe the characteristic features of an insect pollinated flower.  [Delhi 2013] 186. (i) Plan an experiment and prepare a flow chart of the steps that you would follow to ensure 177. (a) Describe the process of megasporo-genesis in that the seeds are formed only from the angiosperms until 8 nucleate stage. desired sets of pollen grains. Name the type (b) Draw the labelled structure of mature embryo of experiment that you carried out. sac.  [All India 2013 C] (ii) Write the importance of such experiments. 178. (a) Draw a labelled diagram of a transverse section of a mature anther of an angiosperm [All India 2015] showing different wall layers. 187. (i) Draw a diagram of an angiospermic embryo sac, where fertilisation is just completed. (b) Mention the function of each of these wall layers during pollen grain development. Label the following parts [Delhi 2013] (a) Micropylar end of embryo sac 179. (a) Differentiate between autogamy, geitonogamy (b) The part that develops into an embryo and xenogamy? (c) The part that develops into an endosperm (b) Explain the events that occur during pollen (d) The degenerating cells at the chalazal end pistil interaction. [All India 2011 C] (ii) Draw a labelled diagram of globular embryonic stage of an angiosperm. [Foreign 2011] 180. Describe in sequence the events that lead to the development of a 3-celled pollen grain from 188. (i) Explain the characteristic features of wind pollinated flowers. How are insect pollinated microspore mother cell in angiosperms. flowers different from them? [Delhi, All India 2010] (ii) Explain the mutually rewarding relationship 181. (a) D e s c r i b e i n s e q u e n c e t h e p r o c e s s o f between Yucca plant and species of moth. megasporogenesis in angiosperms. [Foreign 2011] (b) Draw the seven-celled structure formed and 189. (i) Draw a labelled diagram of L. S. of a flower to label all the different cells. [Delhi 2010] show the growth of pollen tube reaching egg 182. (a) Geitonogamy is functionally a cross pollination apparatus. but genetically similar to autogamy. Explain. (ii) Pistil of a flower does not accept pollen from (b) Why do flowering plants need to develop any plant other than its own kind. How does it happen? Explain. outbreeding devices. Explain any three such (iii) What is syngamy?  [Foreign 2009] devices developed by flowering plants. [All India 2010 C] 190. (i) Mature seeds of legumes are non-albuminous. Then, can it be assumed that double 183. Explain the development of the zygote into an fertilisation does not occur in legumes? embryo and of the primary endospermic nucleus Explain your answer. into an endosperm in a fertilised embryo sac of a (ii) List the differences between the embryos of dicot plant.  [All India 2010 C] dicot (pea) and monocot (grass family). 184. (a) Trace the development of embryo after [Delhi 2014] syngamy in a dicot plant. 191. (i) Draw a labelled longitudinal view of an (b) Endosperm development precedes embryo albuminous seed. development. Explain. (ii) How are seeds advantageous to flowering (c) Draw diagram of a mature dicot embryo plants?[All India 2008, 2010] and label cotyledons, plumule, radicle and 192. (a) When a seed of an orange is squeezed, many hypocotyl in it.  [All India 2009] embryos, instead of one are observed. Explain 185. A flower of tomato plant following the process of how it is possible. 4+1=5 sexual reproduction produces 240 viable seeds. (b) Are these embryos genetically similar or Answer the following questions giving reasons: different? Comment. [All India 2017] (i) What is the minimum number of pollen 193. (a) Describe any two devices in a flowering grains that must have been involved in the plant which prevent both autogamy and pollination of its pistil? geitonogamy. (ii) What would have been the minimum number (b) Explain the events upto double fertilisation of ovules present in the ovary? after the pollen tube enters one of the (iii) How many megaspore mother cells were synergids in an ovule of an angiosperm. involved?  [CBSE 2018] Sexual Reproduction in Flowering Plants  23

Answers I. Multiple Choice Questions 12. Parthenium 13. Refer answer no. 1. 1. (c) 2. (c) 3. (a) 4. (d) 5. (d) 14. Pollen tube arises from the germ pore after 6. (b) 7. (a) 8. (b) 9. (c) 10. (b) 11. (a) 12. (c) 13. (a) 14. (a) 15. (b) pollination. 16. (c) 17. (d) 18. (a) 19. (b) 20. (a) 15. Anemophilous flowers are dull coloured, mostly 21. (d) 22. (d) unisexual, arranged in inflorescence, pollen II. Fill in the Blanks grains light and non-sticky, stigma often feathery. 16. Anthers have two lobes and each lobe has two 1. placenta 2. 2n, diploid cavities in it, so called dithecous. 3. vegetative propagation 4. hypogynous, 17. Pollens are stored for longer period in liquid 5. catkin 6. leaf 7. double 8. pollenium nitrogen in pollen banks. This increase their 9. endosperm 10. synergids. viability and can be used for hybridization when required. III. True or False 18. This is because papaya plants are dioecious and only female plants will bear fruits and male 1. True 2. False 3. True 4. False 5. False plants will not. 6. False 7. True 8. False 9. True 19. Refer answer no. 15. 20. The outer layer exine of pollen grain contains IV. M atch the items of Column I with those of sporopollenin which is chemically a very stable Column II: substance for preservation in soil and sediments. Hence fossils of microscopic pollen grains of the (i) → (b), (ii) → (e), (iii) → (a), (iv) → (c), (v) → (d) past could be obtained from fossils. 21. Unisexual flowers. 1 Mark Questions 22. To protect flower from being pollinated by unwanted pollen. 1. Tapetum provides nutrition to developing pollen 23. Statement 'c' is incorrect grains. If tapetum malfunctions, the pollen grains 24. By cryopreservation (in liquid nitrogen at –196°C) 25. Refer answer no. 17 and 24. will not get nutrition, hence will not be able to 26. (a) Central cell ( b) Synergids. 27. Fusion of one male gamete with egg cell and other develop into viable male gametophytes. male gamete with two polar nucleis is double fertilization. 2. Vallisneria pollen grains are produced under 28. Coleorhiza is the protective sheath over radicle water. They have protective mucilaginous coat to which protects it. 29. Banana develop without fertilization. protect themselves from damaging effect of water. 30. 36 chromosomes 31. Wall of the fruit which develops from ovary wall 3. Coleoptile is a protective sheath on plumule after fertilization is pericarp. It gives protection which protects it. to the seed. In some fruits it is edible, hence also help in seed dispersal. 4. Single cotyledon of monocot seed is scutellum 32. Apomixis. Asteraceae and grasses. which provides nutrition to developing embryo. 33. Strawberry: Thalamus. Guava: Ovary 5. It is due to polyembryony. Cells of nucellus divide 34. Because it develops from thalamus and not from and form embryo sac. So more than one embryo ovary. 35. In hybrid progeny the characters segregate and is present. do not maintain hybrid characters. 36. Development of seed without fertilization is 6. Staminate flowers. called apomixis. It is important in horticulture 7. Only a compatible pollen grain is allowed to and agriculture for hybrid seed industry. 37. Wind pollination. Pollen grains are non sticky. germinate on stigma and is mediated via proteins 38. Advantages of apomictic seeds are:  (i) They reduce the cost of developing seeds by and chemicals present on stigma which are artificial hybridization method. absorbed by compatible pollen grains only. (ii) The desired traits are maintained with no 8. Filiform apparatus guides the pollen tube to enter segregation year after year. embryo sac through synergids. 39. Xenogamy 9. Geitonogamy Xenogamy Pollen grains land on Pollen grains land on the stigma of different the stigma of a flower flower but of same of different plant. plant. 10. Each microspore gives rise to 4 pollen grains, each microsporangium contains 100 microspore mother cells, they will produce 400 microspores. Each anther contains 4 microsporangia at each corner, so the total number of pollen grains will be 400 × 4 = 1600 11. So that they remain protected from wetting. 24 Biology–12

2 Marks Questions Chalazal end Antipodals 40. Exine is made up of sporopollenin and intive is made up of pectocellulose (pectin and cellulose) it Polar nuclei is the most resistant material known till date. Central cell Exine helps in protecting pollen grains, due to Egg sporopollenin the pollens are found fossilised. 41. Mature microspore (a) Vacuole Vegetative cell Exine Synergids Intine Vegetative or Filiform Tube nucleus Micropylar end apparatus Germ pore Generative cell Legend: An Embryo Sac 45. (a) Microsporangium containing micro-spore Mature pollen grain in Angiosperm mother cells which develop into pollen grains. 42. Egg cell, synergids, antipodals are haploid cells. (b) Tapetum, it provides nutrition to develo-ping An embryo sac contains 7 cells. pollen grains. 46. In geitonogamous plants, the pollen grain falls 43. Two cells present in a mature male gametophyte is the vegetative cell and the generative cell. on stigma of another flower on the same plant. Since both the flowers are on same plant, they Vegetative cell Generative cell will be genetically same, so we can say that such Cell is bigger Cell is smaller and floats in flowers are genetically autogamous. As the pollen vegetative cell grain and stigma are of two different flowers so Oval in shape the flower is functionally cross pollinated. Abundant food Spindle shaped 47. Refer answer no. 38 Cytoplasm dense 48. Albuminous seeds Non-albuminous seeds reserve present Nucleus irregular Nucleus dense Endosperm present. Endosperm absent, No role in Mitotically divide into two e.g. Wheat, rice, maize, i t i s c o n s u m e d b y fertilization male gametes and take castor. developing embryo. part in double fertilization. e.g. Pea, coconut 44. Hilum 49. Flower of Brinjal Flower of Beans Funicle • Flower is open with • Flower is closed with exposed stigma and anther dehiscence Micropyle anther within its bud. Anther and stigma Micropylar pole • Cross pollination lie close to each other hence pollinating Outer Integument agents needed • Self pollination and Inner does not require Nucellus pollinating agents Embryo sac Chalazal pole A mature anatropous ovule 50. (a) Epidermis Endothecium Connective Epidermis Middle layers Endothecium Microspore Sporogenous tissue mother cells Tapetum Tapetum Middle layers T. S. of a young anther Microsporangium Sexual Reproduction in Flowering Plants  25

(b) Exine is not a continuous layer as it bears 58. Refer answer no. 44. germ pores from where pollen tube comes out. 59. Refer answer no. 2. 60. Advantage: Ensures self pollination 51. Banana crop is propagated vegetatively by its Disadvantage: Continuous self pollination can underground stem rhizome. lead to inbreeding depression. 52. Endosperm of coconut develops from the central cell. It develops into endosperm after triple 61. Wind pollinated flowers: fusion. (i) Are dull coloured (ii) Have well exposed stigma 53. Banana is a parthenocarpic fruits which develops (iii) Pollen grains are produced in large number without fertilization and is seedless. In the seeds (iv) Pollens are non sticky, dry, unwettable of oranges, some of the nucellar cells surrounding (v) Inflorescence is compact the embryo sac and develop into multiple embryo, (vi) Mostly unisexual so each ovule contains many embryos, showing (vii) Hairy and feathery stigma polyembryony. 62. Development of pollen grains from sporo-genous 54. (i) Autogamy: Pollen grains lands on stigma of tissue is called microsporogenesis. Each cell same flower. of sporogenous tissue (micros-pore mother cell) divides by meiosis to become four haploid (ii) Geitonogamy: Pollen grains lands on stigma cells called pollen tetrad or microspores. Each of different flower but of same plant. microspore divides unequally and forms two cells, the larger is the vegetative cell and the smaller (iii) Xenogamy: Pollen grains land on stigma of is the generative cell. Generative cell becomes different plant. spindle shaped and floats in the cytoplasm of vegetative cell. Generative cell further divides 55. Refer answer no. 18. by mitosis and forms two male gametes. 56. Pistils are free in apocarpous flowers e.g. 63. Endothecium: It is one of the protective layer of Michelia whereas they are fused in syncarpous author flowers, e.g. Papaver 57. To ensure cross pollination and discourage self Tapetum: It provides nourishment to the pollination maturing of stigma & release of developing pollen grains. pollens is not synchronised. Anther and stigma are placed at different positions. 64. Refer answer no. 54. 65. To avoid self pollination. It is not necessary in Two devices are: (i) Protogyny: Stigma mature earlier than the unisexual flowers. anther and get pollinated, e.g. Mirabilis 66. Emasculation is carried out to prevent self jalapa. pollination during hybridisation of bisexual (ii) Protandry: Occurs in bisexual flower where flower whereas bagging is done to prevent stigma and anther mature at different time, contamination of desired pollen grains from e.g. Sunflower. unwanted, accidental pollination by unwanted pollen grains. (iii) Self sterility: Presence of self sterile gene does not allow pollen grains to germinate on the stigma of same flower, e.g. Tobacco. 67. Degenerating synergids Zygote (2n) Primary endosperm Suspensor cell (PEC) Radicle Primary endosperm nucleus (3n) (PEN) Zygote Degenerating Cotyledon Cotyledon antipodal cells Heart-Shaped Embryo Globular Embryo Plumule Mature embryo (b) (a) A mature anatropous ovule 26 Biology–12

68. (a) (i) Unisexual flowers 77. Refer answer no. 44. (ii) Maturation of stigma and pollens at 78. Refer answer no. 41. 79. 1–Antipodals 2–Polar nuclei different time. 3–Central cell 4–egg cell 80. During fertilization in angiosperm two male (iii) Self incompatibility of pollens (iv) Position of anther and stigma is different. gametes are released. One male gamete fuses (b) Refer answer no. 46. with haploid egg to form diploid zygote. It is 69. (a) Bisexual flower are hybridised by emasculation called syngamy. Another male gamete fuses with two polar nuclei to form triploid primary (removal of male reproductive part), stamen endosperm cell. This is called triple fusion and followed by dusting of desired pollen grains referred to as double fertilization. of male flower, bagging and tagging. 81. Refer answer no. 80 (b) In unisexual female parent the unopened 82. For figure refer answer 41. floral buds is bagged with cellophane and on To carry out double fertilisation, two male receptivity of stigma, male pollen grains are dusted followed by bagging. gametes present in the pollen tube fuses with two different cells of female gametophyte of the 70. In mature gametophyte there are six haploid ovule. One fuses with egg cell and other with cells. They are: 3-antipodals, polar nuclei. 2-synergids and 1 egg cell. 83. Refer answer no. 80 71. A–micropyle 84. Refer answer no. 80 B–Outer integument 85. Refer answer no. 67 C–Nucellus 86. Refer answer no. 80 D–Embryo sac 87. Banana is a parthenocarpic fruit as it develops 72. Refer answer no. 46. without fertilization whereas Turkey is 73. Pollen grain parthenogenetic as its egg develop without fertilization. Chalazal end Pollen tube 88. Tender coconut water is free nuclear endosperm whereas thick white kernel is cellular endosperm. Antipodal Both are triploid Polar nuclei Egg cell 89. Synergid Hilum Suspensor Longitudinal section of a flower Radicle showing growth of pollen tube A mature anatropous ovule Central cell Plasma membrane Cotyledon Egg nucleus Synergid Plumule Filiform apparatus Mature Embryo Male gametes 90. In albuminous seeds the endosperm persists, e.g, Vegetative nucleus coconut, maize, wheat etc. Persistent nucellus 74. Refer answer no. 60. when present in seeds it is called perisperm, e.g. 75. Refer answer no. 44. Nymphaea, coffee, castor etc. 76. Geitonogamy: Pollen grains land on the stigma 91. Changes a fertilised ovule undergoes within the ovary are: of different flower but of the same plant. (i) Zygote–Embryo (a) It is genetically similar to autogamy as pollen (ii) Triploid primary endosperm–Endosperm and stigma are of same plant. (may or may not persist) (b) Geitonogamy is equivalent to xenogamy as both (iii) Nucellus–Used up or forms perisperm (iv) Outer integument–Seed coat shows cross pollination, pollen and stigma are of (v) Inner integument–Tegmen different flowers. Sexual Reproduction in Flowering Plants  27

(vi) Micropyle–Fine pore 96. Refer answer no. 94 (vii) Funicle–Stalk of a seed 97. Refer answer no. 89 (viii) Hilum–Point of attachment marked on seed. 98. Refer answer no. 88 92. (a) Free nuclear division occurs in primary 99. For definition refer answer no. 36. Its advantages to the farmers are: endosperm nucleus. Large number of free (i) More productive seeds without segre-gation nuclei are formed, so this stage is called free nuclear endosperm. of genes. (ii) Provides better clones (adventive embryo) Later cell wall formation starts from periphery towards inner side. This gives rise to cellular than cutting. endosperm. (iii) Seeds free from infection (apomictic embryo). These results in highly cost effective and If endosperm is fully consumed by developing embryo, seed is called non-albuminous seed, timely production of crops. and if endosperm persists in seed, it is called 100. Apomictic seed can develop by one of the following albuminous seed. ways: Endosperm development occurs before (i) Recurrent agamospermy: Diploid egg cell the development of embryo to ensure the availability of nutrition for the embryo. is formed without reductional division & develops into embryo without fertilization e.g. (b) It contains all the nutrients required by Mango, Zeamays humans (ii) Adventive embryony: Nucellar cells divides and develop into embryo e.g. citrus, opuntia. (c) Refer answer no. 48 In these species many embryos are found 93. (i) Primary endosperm cell–Endosperm in each ovule. The phenomenon is called (ii) Outer part endosperm–Cellular endosperm polyembryony. (iii) Hybrid plants are artificially developed into (Edible meat) apomictic so that there is no segregation of characters. (iii) Centre endosperm-Nuclear endosperm 101. Refer answer no. 100. (coconut water) 102. (a) Some species of Asteraceae and grass produce seed without fertilization by a process called 94. Pericarp apomixis. (b) Refer answer no. 100. Endosperm 103. • In 2-celled stage the mature pollen grain contains a generative and vegetative cell, Scutellum Coleoptile whereas in 3-celled stage one vegetative cell and two male gametes are present Plumule • The generative cell floats in the cytoplasm of Radicle vegetative cell Coleorhiza 3 Marks Questions Mature Embryo 104. (a) For diagram refer answer no. 41. 95. (a) A–Thalamus (b) Sporopollenin can withstand high temperature B–Ovary C–Endocarp and strong acids and alkali. No known (b) Because it develops from thalamus and not enzyme can degrade sporopollenin. 105. Angiosperm anthers are dithecous because each from ovary. lobe of anther contains two theca. Connective Epidermis Epidermis Endothecium Endothecium Middle layers Sporogenous tissue Tapetum Microspore Middle layers mother cells Tapetum 28 Biology–12

Structure of microsporangium develop without fertilization are parthenocarpic • Anther is bilobed and dithecous because it has fruits. Such fruits are seedless as ovules do not develop. Banana is a parthenocarpic fruit so is two lobes and each lobe has two cavities seedless. • Line of dehiscence opens up to release pollen 112. Perisperm Endosperm grains when anther is mature. (i) It is the residual (i) It is formed by fu- • The section of anther shows a four sided persistant nucellus sion of two polar (tetragonal) structure having four micro- sporangia at each corner. and provides nutri- nuclei and one male Each microsporangia has four walls: tion to the develop- gamete, it provides (i) Epidermis, it is common to all micro- ing embryo. nutrition to devel- sporangia. oping embryo. (ii) Endothecium (ii) It is diploid. (ii) It is triploid. (iii) Middle layers: Epidermis, endothecium and middle layers are protective in nature. (iii) Example: Black (iii) Example: Wheat. pepper. (iv) Tapetum: It provides nutrition to developing pollen grains. Each cell has more than one 113. Chalazal end nucleus and dense cytoplasm. Antipodals 106. Sporopollenin is present in exine of pollen grain. Polar nuclei This is most resistant organic material known till Central cell date. No acid, alkali or enzyme can degrade it. It Egg can withstand high temperature which helps in preserving the pollen grains in nature. Synergids 107. Cliestogamous flower never opens which prevents Filiform the pollens from other plants to land on its Micropylar end apparatus stigma, so cross pollination cannot happen. But self pollination can occur in closed flower, thus A diagramatic representation of the ensuring autogamy. mature embryo sac 108. In autogamous flowers, artificial hybridization The cell which produces endosperm after double ensures cross pollination. fertilization is the central cell. Steps involved are: 114. (a) Sporopollenin is most resistant organic (i) Emasculation: Removal of anthers before material known. No enzyme can degrade it, therefore it is used in preservation of pollen the flower opens up. grains in nature. (ii) Bagging: Flowers are covered by paper bag (b) These locations are germ pores through which which helps to prevent landing of undesirable pollen tube grows out. pollen grains on stigma. (c) The pollens are stored in liquid nitrogen (at (iii) Artificial pollination: When the stigma –196°C) for years. It retains their viability gets receptive, desired pollens are dusted on and are used in crop breeding programme. stigma artificially. 115. (a) Three outbreeding devices in flowering plants (iv) R e b a g g i n g : T h i s a g a i n e n s u r e s t h e are: germination of only desired pollen grains on stigma after artificial pollination. (i) Encouraging cross-pollination–Pollen released and stigma receptivity are not (v) T a g g i n g : W h o l e i n f o r m a t i o n a b o u t synchronised. hybridization is written on a paper and is tagged to a plant. (ii) Different position of stigma and anther– To prevent contact of pollen with stigma 109. Refer answer no. 92 (a) of same flower. 110. (i) Provides nourishment to developing embryo. (ii) Protects embryo from harsh environ-mental (iii) Self-incompatibility–To prevent self- pollen from fertilising the ovules conditions. inhibiting pollen germination. (iii) Helps in dispersal to avoid competition and (iv) Unisexual flower–To prevent autogamy. preventing extinction. (b) Angiosperm anther is dithecous because each 111. Fruits which develop from ovary are true fruits, lobe of anther contains two theca. mango develops from ovary of a flower. Fruit which develop from thalamus or other parts of a flower but not from ovary are called false fruit, apple develops from thalamus. Fruits which Sexual Reproduction in Flowering Plants  29

Structure of microsporangium • Anther is bilobed and dithecous because it has two lobes and each lobe has two cavities • Line of dehiscence opens up to release pollen grains when anther is mature. • The section of anther shows a four sided (tetragonal) structure having four microsporangia at each corner. • Microsporangia develop into pollen sac which in turn contains sporogenous tissue. Sporogenous tissue develops into pollen grains. • Each microsporangia has four walls:  Epidermis–it is common to all micro-sporangia  Endothecium  Middle layers (Epidermis, endothecium and middle layers are protective in nature. Tapetum: it provides nutrition to developing pollen grains. Each cell has more than one nucleus and dense cytoplasm) 116. Refer answer no. 73. 117. Refer answer no. 62. 118. A cell within ovule differentiates and becomes a megaspore mother cell. It divides by meiosis and tetrad is formed. Three cells degenerate and one remains functional. The nucleus of the functional cell divides by mitosis without cell wall formation up to eight nuclei. After rearrangement of nuclei, cell wall formation takes place. Three cells towards chalazal end are called antipodals. One of the cell at micopylar end becomes egg and the two become synergids. Two nuclei remain in the central cell and are called as polar nuclei. • Such development from one functional cell is called monosporic development of embryo sac. • Embryo sac is thus 7-celled and 8-nucleate structure. Micropylar end Micropylar end Nucellus Nucellus Meiosis I Megaspore mother cell Megaspore dyad Micropylar end Dyad Micropylar end Antipodals Mitosis II Megaspore Synergids tetrad Egg Metosis Metosis Metosis Chalazal Maturation Polar nuclei end Central cell Egg 2 polar nuclei Rearrangement 3 cells Tetrad nucleus Two nuclear Four nuclear Antipodals Synergids degenrate, of stage stage Filiform Eight nuclear stage Micropylar end apparatus revaiing cell divides by nutosis (b) The cells that guide the pollen tube to enter embryo sac are synergids. Each synergid is haploid and has filiform apparatus which guides the pollen tube. These cells have a big vacuole. 119. The mode of pollination in Vallisneria is water and in Water Lily is wind or insects. In Vallisneria, female flower reaches surface of water by long stalk. Male flowers and pollens are released on the surface of water. They reach stigma of the female flower and pollinates the flower. The pollinated flower is again retracted 30 Biology–12

back into water for further development. Mode 128. Refer answer no. 61. of pollination in water (hydrophily) 129. Refer answer no. 117. 130. Refer answer no. 73. Female flower 131. (a) A–Epidermis B–Endothecium Stigma C–Tapetum (b) Cells of tapetum has dense cytoplasm Male flower Female flower and more than one nucleus: They provide nourishment to developing pollen grains. 132. Significance of pollination: 120. Refer answer no. 117. (i) It leads to fertilization thereby producing 121. A pollengrain after first unequal mitotic division seeds and fruits for continuity of plant life. (ii) It also leads to genetic recombination and the pollen grain has two cells, larger vegetative variations in progeny. cell and a smaller generative cell. The generative Differences: cell leaves the cell wall and floats in the cytoplasm of vegetative cell. There it divides mitotically and Wind Pollination Animal Pollination gives rise to two male gametes. This is 3 celled pollen grain. (i) Small flower (i) Larger flower Exine (ii) Odour less flower (ii) Scented flower Vegetative nucleus Intine ( iii) Flowers lack ( iii) Nectars present nectars Male Gametes (iv) Dull coloured (iv) Brightly coloured Vegetative cell flower flowers Germ pore 133. Refer answer no. 61 134. Refer answer no. 94 122. Refer answer no. 107. 135. Refer answer no. 80 Importance: Emasculation prevents self 136. Embryo sac develops after meiosis hence cells are haploid. Zygote is formed after fusion of a haploid pollination and Bagging prevents landing of egg cell and a haploid male gamete hence it is unwanted pollen grains on stigma. diploid. 123. Refer answer no. 117. 124. Refer answer no. 114. Two polar nuclei fuse with one male gamete and 125. Refer answer no. 44. form primary endospermic nucleus, hence it is 1 26. (a) (i) Exine in pollen grain inside micro triploid. sporogonium 1 37. Components Fate (ii) Inside ovule of ovary (b) Refer answer no. 41. 1. Egg: 1. Zygote 127. 2. Synergids: 2. Degenerate 3. Central cell with two 3. Primary endosper- polar nuclei: mic nucleus which divides to form endo- sperm 4. Antipodals: 4. Degenerate 138. Refer answer no. 80 139. Development of dicot embryo: Zygote divides to form two cells, a basal cell and a suspenser Pollen tube cell. The suspenser cell further divides to form Antipodal proembryo and then a globular embryo. Globular Polar nuclei embryo further divides to form heart shaped Egg cell embryo and finally into mature embryo. A dicot Synergid embryo has an embryonic axis and two lateral cotyledons. Portion above the level of cotyledon Longitudinal section of a flower is called epicotyl and below is hypocotyl. Epicotyl showing growth of pollen tube contains plumule which gives rise to shoot and hypocotyl contains radicle which gives rise to root. Root tip is covered by a root cap. Sexual Reproduction in Flowering Plants  31

Degenerating synergids Zygote (2n) Primary endosperm Suspensor cell (PEC) Primary endosperm Radicle Radicle nucleus (3n) (PEN) Zygote Plumule Cotyledon Cotyledon Heart-Shaped Embryo Degenerating Globular Embryo Plumule Mature embryo antipodal cells (b) (a) 140. Post fertilization events are: 149. (a) Globular embryo (b) Zygote (c) (i) Zygote formation Suspensor (ii) Embryogenesis Heart-Shaped Embryo (iii) Endosperm development 150. (a) Yes, By artificial means (any relevant (iv) Seed & fruit formation explanation) 141. Two events are syngamy & triple fusion. After (b) Diagram with following labellings syngamy zygote is formed and it gives rise to Stigma, Pollen tube, Synergid / Filiform embryo. After triple fusion PEN is formed which Apparatus, Micropyle gives rise to endosperm. Stigma 142. Refer answer no. 87 Pollen Tube 143. A–Pericarp B–Scutellum C–ColeorhizaD –Coleoptile 144. (a) Albuminous seeds–Castor Non albuminous seeds–Groundnut (b) (i) Nucellus (ii) Integuments (iii) Central cell (iv) egg/zygote 145. Refer answer no. 110 146. Scutellum Coleoptile Synergid Filiform Apparatus Shoot spex Micropyle Epiblast Radicle 151. In Vallisneria pollination takes place through Root cap Coleorhiza water, the submerged female flower reaches the surface of water by long stalk, pollen grains are 147. (a) Refer answer no. 87 released on the surface of water and are carried (b) Persistant nucellus in seeds is perisperm passively by water current reaching the female flowers leading to pollination. In water lily whereas ovary wall develops into fruit wall pollination takes place through wind or insect, called as pericarp. female flower emerges above the surgace of water 148. (a) Refer answer no. 94 and gets pollinated. (b) Refer answer no. 109. 152. Pollen grain may be released at 2-celled stage in which one is vegetative and the other is generative cell. It is released at 3-celled stage 32 Biology–12

in which one is vegetative cell and other two are endosperm. Later cell wall formation takes male gametes which float in vegetative cell. 153. (a) In coconut Primary Endosperm Nucleus place and endosperm becomes cellular. (PEN) undergoes successive nuclear divisions (ii) The endosperm provides nutrition to which give rise to free-nuclear endosperm developing embryo in both groundnut and known as coconut water. Later the cell wall formation takes place and cellular endosperm castor plant is formed, this is white kernel part of the coconut. this provides nutrition to the growing (iii) In groundnut, the endosperm is fully embryo. consumed by embryo and seed becomes non- (b) Pollens are stored in liquid nitrogen in pollen banks and are used in crop breeding albuminous programmes. (iv) In castor, the endosperm persists in mature 5 Marks Questions seed and is not fully consumed, so seeds are albuminous. 162. Refer answer no. 80. Ploidy of cells are haploid before fertilization. For diagram refer answer no. 154. Funicle (e) 94 163. Pollen grain lands on stigma in two cell stage → Micropyle (d) generative cell divides to form two male gametes Central cell (c) → pollen tube grows from germ pore → content of pollen tube moves into pollen tube → pollen tube Integument (a) grows through style and reaches ovary → pollen tube enters through micropyle and enters one of Embryo sac (b) the synergids through filiform apparatus → the pollen tube releases two male gametes in the cytoplasm of synergids, one male gamete fuses with egg cell (syngamy) and gives rise to zygote → other male gamete fuses with two polar nuclei in central cell (triple fusion) and gives rise to PEN. 164. Given: Number of viable seeds = 360 (a) Number of pollen grains which will land on 155. (a) Refer answer no. 112. stigma = 360 (Each pollen grain will fertilize (b) Fate of egg cell: The egg cell fuses with a male one ovule) gamete to form zygote. (b) Number of ovules will be 360 (Number of Fate of polar nuclei: The two polar nuclei fuses fertilized ovule develop into seeds with the other male gamete to form primary endosperm nuclear (PEN) (c) Megaspore mother cells = 360 (Each MMC develops into an ovule) 156. Refer answer no. 61. 360 157. Insect pollinated flowers are: (d) Microspore mother cells = 4 = 90 (i) Brightly coloured (ii) Are fragrant (iii) Contain nectar (Each microspore mother cell gives rise to four (iv) Pollen grains are sticky (v) F l o w e r s m a y b e a r r a n g e d c l o s e l y o n pollen grains after meiosis) inflorescence like in sunflower (e) Male gametes involved = 360 × 2 = 720 (One pollen grain gives rise to two male (vi) Protandry occurs, anthers mature earlier than stigma. gametes) 158. Refer answer no. 107. 165. Given: Total viable seeds = 200 159. Endosperm is formed before the development (a) Number of ovules = 200 (Each ovule after fertilization gives rise to one seed) of embryo because it has to provide nutrition to the developing embryo. In albuminous seeds, the (b) Number of microspore mother cells endosperm acts as a storage tissue and mainly = 2040 = 50, stores starch and fat. Refer Q. 138 for diagrams. (Each microspore mother cell gives rise to four 160. Refer answer no. 80. 161. Groundnut and castor, both are angio-sperms pollen grains after meiosis) so double fertilization will occur in both these plants. Post fertilization events are: (c) Pollen grains = 200 (Each pollen grain will fertilize one ovule) (i) The Primary endospermic nucleus divides repeatedly and gives rise to free nuclear (d) Male gametes = 2 × 200 = 400 (One pollen grain gives rise to two male gametes) (e) Number of megaspore mother cells = 200 (Each MMC develops into an ovule) Sexual Reproduction in Flowering Plants  33

166. Post pollination events are: 170. Refer answer no. 117. (i) Pollen pistil interaction occurs. 171. Refer answer no. 104. (ii) Compatible pollen grain germinates and two 1 72. (a) Vacuole Tube cell male gametes are carried to ovary by pollen Exine Tube nucleus tube. Intine (iii) Syngamy occurs, one male gamete fuses with Germ pore Generative cell egg cell to form zygote. (iv) Triple fusion occurs, other male gamete fuses Mature pollen grain in Angiosperm with polar nuclei to form triploid primary endosperm nucleus. (b) (i) Exine: It can withstand high temperature/ strong acids/alkali. (v) Zygote develops into embryo (ii) Intine: It is a thin and continuous layer made up of cellulose and pectin. (vi) PEN develops into endosperm (iii) Vegetative Cell: It is bigger and has (vii) Ovule develops into seed abundant food reserve. (viii) Ovary develops into fruit (iv) Generative Cell: It divides mitotically to For different types of pollination depending on give rise to two male gametes. source of pollen grains Refer answer no. 54. 173. (a) Refer answer no. 50. 167. (a) Refer answer no. 117. (b) Refer answer no. 62. (b) The cells that guide the pollen tube to enter 174. (a) Refer answer no. 62. (b) Refer answer no. 167. embryo sac are synergids. Each synergid is 175. • Monoecious plants have both male and female haploid and has filiform apparatus which guides flowers. It ensures cross pollination hence the pollen tube. These cells have a big vacuole. 168. (a) Endothecium (iii) outbreed. Middle layers (ii) Microspore • Cleistogamous flowers does not open at all. They mother cells (iv) are essentially self pollinated, thus inbreed. Endothecium Tapetum (i) • Self-incompatibility: The pollens of self plant Middle layers Tapetum do not germinate on the pistil. This ensure cross pollination and hence outbreed. (b) Cells of the tapetum possess dense cytoplasm and generally have more than one nucleus. It 176. (a) Refer answer no. 163 (a) nourishes the developing pollen grains. (b) Refer answer no. 152. (c) (i) Pollen grains are well preserved as fossils 177. (a) Refer answer no. 117. due to presence of sporopollenin which is (b) Refer answer no. 112. non-degradable organic matter. 178. (a) Refer answer no. 104. (ii) Pollens are believed to be nutrient rich (b) Refer answer no. 104. and provide energy, so are consumed as tablets. 1 79. (a) Refer answer no. 54. (b) Landing of pollen grain on a compatible pistil 169. Refer answer no. 62 → germination of pollen grain → pollen releases its contents in pollen tube → pollen grows through style and reaches ovary → male gametes are released in synergids for fertilization.  180. Refer answer no. 62. 181. (a) Refer answer no. 117. (b) Refer answer no. 112. 1 82. (a) Refer answer no. 46. (b) Refer answer no. 114. 183. Refer answer no. 138 and 92. 184. (a) Refer answer no. 138. (b) Refer answer no. 154. (c) Refer answer no. 89 185. Given number of seeds = 240 (i) 240 (ii) 240 (iii) 240 240 (v) 240 × 2 = 480 (iv) 4 = 60 For explanation refer answer no. 160. 34 Biology–12

186. (i) To produce seeds from desired pollen grains (compatible) and wrong type (incompatible) a process of artificial hybridisation is carried which is mediated by some chemicals of pistil and pollen grains out. This is followed by emasculation and (iii) Fusion of male and female gamete to form bagging. zygote is called syngamy Emasculation anthers Bagging protecting 190. (i) Double fertilization also occurs in legumes. removed stigma The endosperm developed is completely consumed by developing embryo. So they are Artificial pollination Selected pollen Rebagging non-albuminous seeds. dusted georfmpoinllaetnison Tagging (information of hybridization) (ii) Importance: (ii) Dicot Embryo Monocot Embryo (a) Genetic recombination of desired quality Two cotyledons are Only one cotyledon and characteristics. present is present called scutellum (b) Cost effective creation of seed, thereby production of crops. Coleorhiza and Coleorhiza and coleoptile absent coleoptile present 187. (i) Micropylar (a) egg (b) (after fertilization zygote) Cotyledon is on both Cotyledon is present sides of embryonic on (Lateral) side of central cell (c) axis embryonic axis (after fertilization PEN) 191. (i) Refer diagram answer no. 94. antipodals (d) (ii) Refer answer no. 109. 192. (a) Polyembryony, nucellar cells surrounding (ii) embryosac start dividing, protrude into the Globular embryo embryo sac and develop into many embryos 1 88. (i) Refer answer no. 61 & 152. (b) These embryos are genetically similar, as (ii) Yucca & moth both cannot complete their produced from nucellar cells by mitotic division / formed without fertilisation life cycle without each other. The moth lay (but different from the embryo formed by eggs in the ovary and the flower in turn gets fertilization) pollinated. The larvae of moths come out of eggs as the seeds starts developing. 193. (a) Two devices in flowering plants which prevent both autogamy and geitonogamy are- 189. (i) Refer answer no. 73. (ii) A pistil can recognize the pollen of right (i) Dioecy: the plant can either be male or female. Example: papaya (ii) Self incompatibility-genetic mechanism in which plant prevents own pollen from fertilizing the ovule by inhibiting pollen germination. (b) Events after male gametes enter synergids: Pollen tube releases two male gametes into the cytoplasm of synergid one male gamete fuses with the nucleus of The other male gamete moves into central the egg cell. It is called as syngamy which cell and fuses with the two haploid polar results in the formation of diploid zygote. nuclei. This is called triple fusion and results in the formation of triploid PEN. Sexual Reproduction in Flowering Plants  35

Assertion & Reason Type Questions For question numbers 1-15: Two statements 8. Assertion (A): Nucellus functions as a nutritive are given one labelled Assertion (A) and the other tissue. labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given Reason (R): Nucellus is always exhausted below. completely during development of embryo sac. (a) Both Assertion and Reason are true and Reason 9. Assertion (A): Placenta is tissue present inside is the correct explanation of Assertion. the ovary. (b) Both Assertion and Reason are true but Reason Reason (R): Placenta bears ovules. is NOT the correct explanation of Assertion. 10. Assertion (A): Megaspore mother cell undergoes (c) Assertion is true but Reason is false. meiotic division. (d) Assertion is false and Reason is also false. Reason (R): All four megaspores form female 1. Assertion (A): Perisperm is protective covering gametophyte. of seed and helps in dispersal and nutrition. 11. Assertion (A): The egg apparatus consists of two Reason (R): Pericarp is covering of fruit which synergids and one egg cell. is non-functional. Reason (R): Filiform apparatus play an 2. Assertion (A): Ubisch bodies are produced by important role in guiding the pollen tubes into glandular tapetum. the synergids. Reason (R): Ubisch bodies participated in the 12. Assertion (A): Chasmogamous flowers require pollinating agents. thickening of exine. Reason (R): Cleistogamous flowers do not expose 3. Assertion (A): Anemophily is non-directional. their sex organs. Reason (R): Entomophily is highly specific and 13. Assertion (A): Cross pollination is the only means of pollination in unisexual flowers. directional. Reason (R): Self sterility is the only way to 4. Assertion (A): One pollen mother cell forms four prevent self-pollination in bisexual flowers. 14. Assertion (A): Allogamy includes both microspores. geitonogamy and xenogamy. Reason (R): Microspores are formed due to Reason (R): Allogamy needs abiotic or biotic external agencies for pollination. reduction division. 15. Assertion (A): Most of entomophilous pollination 5. Assertion (A): Mostly in a tetrad, all microspores is done by bees. Reason (R): Bee-pollinated flowers are highly are free. coloured. Reason (R): Compound pollen grain and Answers pollinium are formed by grouping of microspores. 6. Assertion (A): Pollen wall is made up of two 1. (d) 2. (b) 3. (b) 4. (a) 5. (b) 6. (c) 7. (b) 8. (c) 9. (b) 10. (c) walls the intine and the exine. 11. (b) 15. (b) Reason (R): Both the walls have depositions of 12. (b) 13. (c) 14. (b) sporopollenin. 7. Assertion (A): Pollen grains of many insect pollinated species are sticky. Reason (R): In the anemophilous flower, the pollen grains are powdery and non-sticky. Case Based Questions 1. The pollen grains or microspores are the (i) One of the most resistant biological material male reproductive bodies of a flower and are contained in the pollen sac or microsporangia. present in the exine of pollen grain is Each pollen grain consists of a single microscopic cell, possessing two coats: the exine and (a) pectocellulose the intine. The exine of a pollen grain is made of chemically stable material. Because (b) sporopollenin of this, pollen grains are often very well preserved for thousands of years in soil and (c) suberin (d) cellulose sediments. (ii) The exine possesses one or more thin places known as (a) raphe (b) germ pores (c) hilum (d) endothecium 36 Biology–12

(iii) What is the function of germ pore? (ii) Which of the following best describes the function of the pollen tube? (a) Emergence of radicle (a) It acts as a conduit to transport male (b) Absorption of water for seed germination gametes from the anther to the ovule. (c) Initiation of pollen tube (b) It acts as a conduit to transport male (d) All of these gametes from the stigma to the ovule. (iv) What is the key advantage to the plant for (c) It contains key nutrients that serve to having such strong pollen grain walls? nourish the newly formed zygote. (a) It protects the vital genetic material in (d) It digest the tissues of the stigma, style the pollen grain. and ovary. (b) It allows pollen to serve as a valuable fossil (iii) Pollination of a flower in which the pollen is carried by an insect is called record for the study of ancient plants. (c) It prevents the pollen tube from growing (a) anemophily (b) ornithophily out before the pollen grain reaches the (c) entomophily (d) malacophily stigma of a compatible species. (iv) Refer to the given characteristics of some (d) It gives weight to the pollen grain allowing flowers. it to cling better to the body surfaces of A. The stamens hang out of the flower insect pollinators. exposing the anthers to the wind. (v) The number of germ pores in dicots and B. The pollen grains are tiny and light. monocots respectively are C. The flower has a sweet scent. (a) one and three (b) three and two D. The flower petals are brightly coloured. (c) two and three (d) three and one How many of the above characteristics are of 2. Cross pollination is the transfer of pollen grains insect pollinated flower? from the anther of a flower to the stigma of a (a) One (b) Two genetically different flower. It is performed with (c) Three (d) Four the help of an external agency which may be (v) Pollenkitt is generally found in abiotic (e.g. wind, water) or biotic (e.g. insects, (a) anemophilous flowers birds, bats, snails). The diagram shows the carpel (b) entomophilous flowers of an insect pollinated flower. (c) ornithophilous flowers (d) malacophilous flowers 3. Pollen-pistil interaction is the group of events that occur from the time of pollen deposition over the stigma to the time of pollen tube entry into ovule. It is a dynamic process which has checks at several places for promotion or inhibition of pollen growth. Pollen-pistil interaction is a safety measure to ensure that illegitimate crossing do not occur. Compatibility and incompatibility of the pollen-pistil is determined by special proteins. (i) What is the most likely reason for non The compatible policies are able to absorb water germination of pollen grain Z? and nutrients from the surface of the stigma. (a) Pollen grains X and Y were brought to the stigma earlier, therefore, their They germinate and produce pollen tubes. Pollen germination inhibited the germination of pollen grain Z. tubes grow into the style. Their growth and path (b) Pollen grain Z was brought to the flower through the style are also determined by specific by wind, while pollen grains X and Y were brought to the flower by insect. chemicals. (c) Pollen grain Z lacks protrusions that allow (i) Which of the following paths of gynoecium it to adhere properly onto the stigma determines the compatible nature of pollen? surface. (a) Stigma (b) Style (d) Pollen grain Z comes from a flower of an incompatible species. (c) Ovary (d) Thalamus (ii) In Trifolium, which type of self-incompatibility is found? (a) Gametophytic self-incompatibility (GSI) (b) Sporophytic self-incompatibility (SSI) (c) Both GSI and SSI (d) None of these. Sexual Reproduction in Flowering Plants  37

(iii) Select the incorrect statement. sexual reproduction but produces seeds without (a) In Asteraceae, incompatibility is due to fertilization. There are several methods of apomictic the genotype of the sporophytic stigmatic development in seeds. The two common ones are tissues. recurrent agamospermy and adventive embryony. (b) In members of Brassicaceae, incompat- (i) Apomixis is a type of reproduction in plants in which ibility is due to the genotype of the pollen. (a) fertilization does not take place (c) Nature has imposed self-incompatibility to avoid highly homozygous individuals (b) male nucleus takes part in fertilization which have a very low survival value. (c) pollen fusion takes place (d) None of these. (d) generative nucleus takes part in fertili- zation. (iv) Which of the following are the examples of self-incompatibility? (ii) Which of the following statements is incorrect regarding recurrent agamospermy? (a) Tobacco (b) Potato (a) It is the formation of seed that has an (c) Crucifers (d) All of these. embryo formed without meiosis and (v) Given figure shows the pollen-stigma syngamy. interaction, where pollen wall proteins are (b) All the cells of embryo sac are diploid. released onto the pellicle of stigmatic papillae, (c) An embryo develops directly from a where recognition reaction occurs. diploid cell other than egg like that of Pollen grain nucleus and integuments. Pollen wall proteins (d) None of these. Pellicle Cuticle (iii) Adventive embryony is found in Pecto-cellulosic wall (a) Citrus (b) Opuntia Plasmalemma (c) Apple (d) Both (a) and (b) (iv) Formation of embryo directly from diploid egg without fertilization is called (a) apospory (b) diplospory (c) polyembryony Callose (d) diploid parthenogenesis (v) If any somatic cell of sporophyte produces gametophyte without reduction division, it is called (a) parthenogenesis (b) apogamy P Q (c) apospory (d) amphimixis Which of the following statements drawn from 5. The endosperm makes the main source of food for the embryo. Generally, the endosperm nucleus given figures is incorrect? divides after the division of the oospore, but in (a) P indicates compatible reaction in which several cases the endosperm is formed to a great the pollen tube penetrates the cuticle and extent even before the first division of the oospore. grows down the papilla. There are three general types of endosperm (b) Development of callose plug between the formation: (a) nuclear type, (b) cellular type, plasma membrane and pectocellulosic and (c) helobial type. The endosperm is usually layer of stigmatic papillae results in the triploid but haploid endosperm is also found. Endosperm may either be completely consumed incompatibility reaction in Q. by the developing embryo before seed maturation (c) A callose plug which appears at the tip or it may persist in the mature seed. of pollen in Q, is dissolved by callase (i) Haploid endosperm is found in enzyme secreted by stigma resulting in (a) Pinus (b) cauliflower compatibility reaction. (c) sunflower (d) pea (d) Deposition of callose can be employed as a reliable bioassay to detect compatibility (ii) Persistent endosperm is found in or incompatibility reactions of pollen and P. Pea Q. Castor stigma. R. Bean S. Coconut 4. Apomixis is a mode of reproduction which does T. Groundnut not involve formation of zygote through gametic (a) Q and S (b) P and T fusion. In plants, apomixis commonly mimics (c) R, S and T (d) P, S and T 38 Biology–12

(iii) Milk of tender coconut represents ...(i)... (b) The primary endosperm nucleus divides and the surrounding white coconut meal earlier than the zygote. represents ...(ii)... . (c) Both the zygote and primary endosperm (i) (ii) nucleus divide simultaneously. (a) cellular f ree-nuclear (d) Both the zygote and primary endosperm endosperm endosperm nucleus undergo a resting period. (b) free-nuclear cellular endosperm Ans. 1. (i) (b) (ii) (b) endosperm (iii) (c) (iv) (a) (v) (d) (c) helobial cellular endosperm 2. (i) (d) (ii) (b) endosperm (iii) (c) (iv) (b) (v) (b) (d) free-nuclear helobial endosperm 3. (i) (a) (ii) (a) (iii) (b) (iv) (d) endosperm (v) (c) 4. (i) (a) (ii) (c) (iv) If an endosperm cell of a gymnosperm (iii) (d) (iv) (d) contains 12 chromosomes, the number of (v) (c) 5. (i) (a) (ii) (a) chromosomes in each cell of the root will be (iii) (b) (iv) (b) (v) (b) (a) 4 (b) 24 qqq (c) 16 (d) 6 (v) In angiosperms, normally after fertilization (a) the zygote divides earlier than the primary endosperm nucleus Sexual Reproduction in Flowering Plants  39

2 Human Reproduction Topics Covered 2.2 Gametogenesis 2.4 Fertilization and Implantation 2 .1 Structure of Male and Female Reproductive System 2.6 Parturition and lactation 2.3 Menstrual Cycle 2 .5 Pregnancy and Embryonic Development C hapter map HUMAN REPRODUCTION Male Reproductive Gametogenesis Female Reproductive System System Accessory Principal Principal Accessory Menstrual glands organs organs glands cycle Seminal Oogenesis vesicle Spermatogenesis Testis Sperm Ovum Ovary Mammary Menstrual glands phase Prostate gland SEMEN Seminiferous Fertilization Fallopian Follicular tubules tube phase Uterus Bulbourethral Vas Zygote Ovulatory gland deferens phase Penis Implantation Vagina Luteal phase Feotal development and Parturition Lactation placenta formation Topic 1. Structure of Male and Female Reproductive System Male Reproductive System Within testis, there are about 250 compartments called testicular lobules and 2–3 highly coiled tubular Male reproductive system is located in the pelvis seminiferous tubules. Male germ cells in seminiferous region. It is composed of a pair of testes, accessory tubule produce sperm after meiosis, sertoli cells ducts, accessory gland and the external genitalia. give nutrition to sperm development. Leydig cells or interstitial cells present outside seminiferous tubules Testes: They descend in scrotum which helps to secrete androgens like testosterone. maintain 2–2.5oC temperature lower than abdomen which is necessary for efficient spermatogenesis. 40

Male Reproductive System Accessory Ducts: Sperms produced in seminiferous tubule move via rete testes, vasa efferentia, epididymis into vas deferens which join with urethra and become common ejaculatory duct and open into urethral meatus. Accessory Glands: Include a pair of each seminal vesicle and bulbourethral gland, a single prostate gland. The secretions of these glands provide nutrition for sperm movement and lubrication of penis. External Genitalia: Penis with an enlarged end called glans penis covered by a foreskin. It is made up of tissue which helps in erection of the penis for insemination. Female Reproductive System Pair of Ovaries: It is located in the lower abdomen. Each ovary encloses soft tissue called stroma. In stroma, different stages of developing follicles are seen. It also produces ovarian hormones. Female Accessory Ducts: It consists of fallopian tube, uterus, cervix and vagina. Fimbriae present at the mouth of fallopian tube called infundibulum collects ovum from ovary. Fertilization occurs in ampulla isthmus junction. Uterus has three layers: perimetrium (protective covering), myometrium Female Reproductive System (muscular layer contracts during child birth) and endometrium (place of implantation of embryo, undergoes cyclic changes during menstrual cycle). Section of Mammalian Ovary External Genitalia: Comprise of mons pubis, labia majora, labia minora, hymen and clitoris. Mammary Glands: Comprise of glandular tissue to secrete milk which is divided into 15-20 mammary lobes containing clusters of cells called alveoli. When milk is produced it passes from alveoli to mammary duct and sucked out by lactiferous duct. Human Reproduction  41

Topic 2. Gametogenesis movement and tail helps in movement. Spermatogenesis Oogenesis • Germ cells → mitosis → oogonia → primary oocyte • Gonadotropin (GnRH) releases hormone from hypothalamus → stimulates pituitary gland (arrested at prophase-I), gets surrounded by granulose → Luteinising hormone (LH) (acts on leydig cells, called primary follicle → more granulose cells cells to secrete androgens) and follicle stimulating with theca called secondary follicle → fluid filled hormone (FSH) (acts on sertoli cells to secrete antrum appears, theca becomes two layered and is spermatogenetic factors) are secreted. called tertiary follicle → Ist meiotic division complete, secondary oocyte is formed, follicle matures and becomes graafin follicle → ruptures to release ovum. Schematic representation of Spermatogenesis Schematic representation of Oogenesis • Male germ cell (spermatogonium) → mitosis → • During coitus, about 200-300 million sperms are primary spermatocyte → meiosis-I → secondary released, 60% of sperms should be of normal shape and spermatocyte → meiosis–II → spermatids → 40% should be vigorously motile for normal fertilization. spermiogenesis → spermatozoa → spermiation (release of spermatozoa from seminiferous tubule) • Spermatozoa have head, middle piece and a tail. Head contains nucleus and at the tip of head enzyme filled cap like structure acrosome is present, it helps the sperm to penetrate the egg. Middle piece has mitochondria which gives energy for sperm Topic 3. Menstrual Cycle Menarche: Start of menstrual cycle at the age of 12-13 years or puberty. Menopause: End of menstrual cycle in and around the age of 50 years in human female. Menstrual cycle is of 29 days. This is summarized as below: Menstruation Follicular phase Ovulation Luteal phase Next cycle begins Day 14-15 Day 1-5 Day 6-13 Day 16 – 26 Day 27-29 • Starts with first day • LH and FSH • LH and FSH • LH and FSH • If no fertilization, of bleeding gradually increases is very high, decreases corpus luteum causes ovulation degenerates • Lasts for 3-5 days • Estrogen is • Estrogen is at • Corpus luteum • Progesterone level produced by ovary peak secretes falls suddenly progesterone • Endometrium • Uterine wall is • Endometrium • Uterine wall • Uterine wall breaks down, repaired lining is grows and breaks blood along with growing is ready for unfertilized ovum implantation flows out of vagina • Bleeding starts and next cycle begins 42 Biology–12

Diagrammatic Representation of Menstrual Cycle Topic 4. Fertilization and Implantation • During fertilization, sperm comes in contact with zona pellucida of ovum → Induces changes in membrane and blocks the entry of other sperms → Sperm enters the cytoplasm of ovum through zona pellucida and plasma membrane with the help of enzymes of acrosome → Nucleus enters the cytoplasm of ovum → This initiates the completion of 2nd meiotic division → Haploid ovum and second polar body is formed → Two nuclei fuse and zygote is formed. • If sperm with X chromosome fuses with egg then female child will develop from zygote and if Y chromosome fuses with egg then male child will develop. • Repeated mitosis occurs in zygote, morula is formed Transport of Ovum, Fertilisation and Passage of Growing with 8-16 cells, each cell is called blastomere → Embryo through Fallopian Tube Blastomere are rearranged, outer layer trophoblast and inner cell mass is formed → Blastocyst reaches uterus, trophoblast attaches to uterus, endometrium grows and covers the blastocyst, this is called implantation. It is the beginning of pregnancy. Human Reproduction  43

Topic 5. Pregnancy and Embryonic Development • Finger like projections called chorionic villi appear from these germ layers. These cells are also called as stem cells. on trophoblast which becomes interdigitated with • Major events which occur during pregnancy are: maternal tissue. It is placenta which provides One month: first sound of heart Second month: limbs and digits formed nutrition and oxygen to embryo, removes pCrOod2uacneds First trimester: all major organs formed other wastes, from embryo. Placenta also Fifth month: hair on head appear Second trimester: body covered with fine hair, hormones like Human Chorionic Gonadotropin eye-lids separate, eye lashes formed (HCG), Human Placenta Lactogen (HPL), estrogens, End of nine months: foetus fully developed. Progestogens. Relaxin is produced at the end of pregnancy by ovary. • Inner cell mass differentiates into embryo → Cells rearrange to form three germ layers: ectoderm, mesoderm and endoderm. All other organs develop Topic 6. Parturition and lactation foetus is expelled out through birth canal, after the placenta is also expelled. • Expulsion of fully developed foetus from uterus is called parturition. • Mammary glands of mother start producing milk (lactation). • Foetus sends signals to pituitary gland which induces mild uterine contractions, this is called • Milk produced during initial days of lactation is foetal ejection reflex → This induces pituitary to called colostrum, it contains several antibodies and produce oxytocin which in turn acts on uterus and is helpful for the baby to develop resistance against increases the frequency of contraction of uterine diseases. muscles → The cycle remains continuous till the EXERCISE I. Multiple Choice Questions (ii) Prostate (iii) Urethra 1. Choose the incorrect statement from the following: (iv) Bulbourethral gland (a) In birds and mammals internal fertilisation (a) (i) and (ii) (b) (i), (ii) and (iv) takes place (c) (ii), (iii) and (iv) ( d) (i) and (iv) (b) Colostrum contains antibodies and nutrients 5. Spermiation is the process of the release of sperms from: (c) Polyspermy in mammals is prevented by the chemical changes in the egg surface (a) Seminiferous tubules (b) Vas deferens (d) In the human female implantation occurs (c) Epididymis (d) Prostate gland almost seven days after fertilization 6. Mature Graafian follicle is generally present in the ovary of a healthy human female around stet: 2. Identify the correct statement from the following: (a) High levels of estrogen triggers the ovulatory (a) 5 – 8 day of menstrual cycle surge (b) 11 – 17 day of menstrual cycle (b) Oogonial cells start to proliferate and give (c) 18 – 23 day of menstrual cycle rise to functional ova in regular cycles from (d) 24 – 28 day of menstrual cycle puberty onwards. 7. Acrosomal reaction of the sperm occurs due to: (c) Sperms released from seminiferous tubules (a) Its contact with zona pellucida of the ova are highly motile. (b) Reactions within the uterine environment of (d) Progesterone level is high during the post the female ovulatory phase of menstrual cycle. (c) Reactions within the epididymal environment of the male 3. Spot the odd one out from the following structures with reference to the male reproductive system: (d) Androgens produced in the uterus (a) Rete testis (b) Epididymis 8. Which one of the following is not a male accessory gland? (c) Vasa efferentia (d) Isthmus (a) Seminal vesicle (b) Ampulla 4. Seminal plasma, the fluid part of semen, is contributed by. (c) Prostate (i) Seminal vesicle (d) Bulbourethral gland 44 Biology–12

9. The immature male germ cells undergo division to 7. Blastocyst become embedded in the endometrium produce sperms by the process of spermatogenesis. of the uterus and is called _____ . Choose the correct one with reference to above. 8. The process of fusion of a sperm with an ovum is (a) Spermatogonia have 46 chromosomes and called ______ . always undergo meiotic cell division III. True or False (b) Primary spermatocytes divide by mitotic cell 1. Sertoli cells synthesise and secrete testicular division hormones called androgens. (c) Secondary spermatocytes have 23 chromo- 2. The male reproductive system is located in the somes and undergo second meiotic division pelvis region. (d) Spermatozoa are transformed into spermatids 3. Sperm are produced by the female reproductive 10. Which among the following has 23 chromosomes? system. (a) Spermatogonia (b) Zygote 4. The oviduct, uterus and vagina constitute the (c) Secondary oöcyte (d) Oögonia female accessory ducts. 5. Ovaries are found in the male reproductive 11. Which of the following hormones is not secreted by human placenta? system. 6. Spermatogenesis starts at the age of puberty. (a) hCG (b) Estrogens 7. The infundibulum leads to a wider part of the (c) Progesterone (d) LH oviduct called ampulla. 8. Sertoli cells are released from the seminiferous 12. The vas deferens receives duct from the seminal vesicle and opens into urethra as: tubules by the process called spermiation. 9. The process of formation of a nature female (a) Epididymis (b) Ejaculatory duct gamete is called spermatogenesis. (c) Efferent ductile (d) Ureter 10. The seminal plasma along with the sperms 13. Urethral meatus refers to the: constitute the ovum. (a) Urinogenital duct (b) Opening of vas deferens into urethra (c) External opening of the urinogenital duct IV. Match between the following representing parts of the sperm and their functions and (d) Muscles surrounding the urinogenital duct choose the correct option. 14. Select the correct option for Human Chorionic Gonadotropin (HCG) released during embryonic development in humans. [CBSE 2022] 1. Column I Column II (i) Helps in maintenance of pregnancy. (i) Enzymes (A) Head (ii) Sperm motility (ii) Leads to rupture of Graafian follicle. (B) Middle piece (iii) Cause strong uterine contraction during childbirth. (C) Acrosome ( iii) Energy (iv) Brings metabolic changes in the mother. (D) Tail (iv) Genetic material (a) (i) and (ii) (b) (i) and (iv) Options: (a) (A) (ii), (B) (iv), (C) (i), (D) (iii) (c) (ii) and (iii) (d) (ii) and (iv) 15. The source of gonadotropin LH and its (b) (A) (iv), (B) (iii), (C) (i), (D) (ii) corresponding function is [CBSE 2022] (c) (A) (iv), (B) (i), (C) (ii), (D) (iii) (a) Anterior pituitary, ovulation (d) (A) (ii), (B) (i), (C) (iii), (D) (iv) (b) Anterior pituitary, Graafian follicle formation 2. Match the following and choose the correct (c) Hypothalamus, Ovulation options: (d) Hypothalamus, Graafian follicle formation Column I Column II (A) Trophoblast II. Fill in the Blanks (i) Embedding of 1. The first menstruation begins at puberty and is (B) Cleavage blastocyst in the endometrium called ______ . (C) Inner cell 2. The process of formation of a mature female mass (ii) Group of cells that would differentiate gamete is called _____ . as embryo 3. The corpus luteum secretes large amounts of ( iii) Outer layer of ______ . blastocyst attached 4. The tertiary follicle further changes with the to the endometrium mature follicle or _____ . (D) Implantation (iv) Mitotic division of 5. The process of delivery of the fetus is called ___ . zygote 6. The milk produced during the initial few days of lactation is called _____ . Human Reproduction  45

Options: 20. Define spermiogenesis. Where does it occur? (a) (A) (ii), (B) (i), (C) (iii), (D) (iv) [Delhi 2008 C] (b) (A) (iii), (B) (iv), (C) (ii), (D) (i) (c) (A) (iii), (B) (i), (C) (ii), (D) (iv) 21. Sperms have a tail whereas eggs do not. Why so? (d) (A) (ii), (B) (iv), (C) (iii), (D) (i) [All India 2007] 1 Mark Questions 22. Name the phase of menstrual cycle when a Graafian follicle transforms into an endocrine 1. Why are human testes located outside the structure. Write its action thereafter. abdominal cavity? Name the pouch in which they [Delhi 2013 C] are present.  [All India 2014] 23. Write the physiological reason, why a woman generally cannot conceive a child after 50 years 2. Write the location and function of the following in human testes.  [All India 2014] of age? [All India 2013 C] (i) Sertoli cells (ii) Leydig cells 24. Mention the function of zona pellucida. [Delhi 20015 C, 2013] 3. Mention the difference between spermato-genesis and spermiation. [Delhi 2012] 25. How does the sperm penetrate through the zona pellucida in human ovum? [Delhi 2013 C] 4. What happens to corpus luteum in human female if the ovum is (i) fertilized, (ii) not fertilized? 26. Identify the figure below and the part labelled “A”.[All India 2013] [All India 2015 C] A 5. How does colostrum provide initial protection against diseases to a new born infant? [Delhi 2009] 6. How is the entry of only one sperm and not many ensured into an ovum during fertilisation in 2 Marks Questions humans?[All India 2012] 27. State the role of oxytocin in parturition. What 7. Mention the function of trophoblast in human triggers its release from the pituitary? embryo.[Delhi 2011] [Foreign 2016] 8. Name the embryonic stage that gets implanted in the uterine wall of human female. 28. Where does fertilisation occur in humans? Explain the events that occur during this process. [All India 2011] [All India 2014] 9. Where is acrosome present in humans? Write its function. [All India 2012] 29. Where are fimbriae present in human female reproductive system? Give their function. 10. List the changes the primary oocyte undergoes in the tertiary follicular stage in the human ovary. [Delhi 2009] [Foreign 2011] 30. Draw and label the parts on the head region only of a human sperm. [All India 2014 C] 11. Name the cells that nourish the germ cells in the testes. Where are these cells located in the testes? 31. Explain the hormonal regulation of the process of spermatogenesis in humans. [All India 2013] [All India 2013 C] 32. Where are leydig cells present? What is their role 12. Write the location and function of sertoli cells in in reproduction?  [All India 2009] humans.[Delhi 2012] 33. Write the location and function of myometrium 13. Give reason for the following: and endometrium.  [Delhi 2011 C] The human testes are located outside the abdominal cavity. [All India 2012] 34. Explain the events that follow upto fertilization when the sperms come in contact with the ovum 14. W h y d o e s f a i l u r e o f t e s t e s t o d e s c e n d into the scrotum produce sterility?  in the fallopian tube of a human female. [All India 2007] [All India 2014 C] 15. What is the function of Leydig’s cells? 35. When and where do chorionic villi appear in [All India 2007] humans? State their function. [Delhi 2013] 16. Write the function of (oviductal) fimbriae. 36. Write the effect of the high concentration of LH [Delhi 2012] on mature Graafian follicle. [All India 2014] 17. When do the oogenesis and the spermato- 37. Differentiate between major structural changes genesis initiate in human females and males in the human ovary during the follicular and luteal phase of the menstrual cycle. respectively?  [Delhi 2012] [All India 2010] 18. Write the function of acrosome of human sperm. [Delhi 2012] 38. Differentiate between menarche and menopause. 19. When does oogenesis begin? [All India 2010 C] [All India 2010] 46 Biology–12

39. Mention the role of gonadotropins in menstrual 54. Differentiate between gametogenesis in human cycle. On what day of the menstrual cycle do the males and females on the basis of gonadotropins reach a peak? [All India 2009 C] (a) Time of initiation of the process. 40. Explain the role of Sertoli cells in the development of sperms. [Delhi 2010 C] (b) Products formed at the end of the process. 41. Why are the human testes situated in the [All India 2008] scrotum outside the abdomen? [Delhi 2010 C] 55. Mention the sites of action of the hormones GnRH and FSH during spermatogenesis in human 42. Draw a labelled diagram of the human female reproductive system.  [Delhi 2011] males. Give one function of each of the hormones. [All India 2008 C] 43. Explain the functions of myometrium and 56. At what stage of menstrual cycle is corpus luteum endometrium in human females.[Delhi 2011 C] formed in human females? When does it regress? 44. Mention the names and the characteristics of [Delhi 2010 C] different uterine wall layers in human. Which 57. Name the muscular and the glandular layers one of them undergoes cyclic changes during of human uterus. Which one of these layers menstrual cycles? [Delhi 2011 C] undergoes cyclic changes during menstrual cycle? 45. Write two major functions each of testes and Name the hormone essential for the maintenance ovary.[Delhi 2008 C] of this layer. [Delhi 2009] 46. Explain the role of pituitary and sex hormones 58. Name the hormones influencing in the process of spermatogenesis. (a) ovulation, [All India 2015 C] (b) development of corpus luteum. 47. Draw a detailed structure of a human sperm. [All India 2009 C] Label the cellular components. [Delhi 2013 C] 59. List the different parts of the human oviduct 48. Mention the event of meiosis that occurs in the through which the ovum travels till it meets the tertiary follicle in a human ovary.[Delhi 2013 C] sperm for fertilisation. [Delhi 2014 C] 49. Draw labelled diagram of a human sperm. 60. Name the stage of the human embryo that gets implanted in the uterus and draw its labelled [All India 2008, 2013 C] diagram.[All India 2013 C] 50. Write the function of each of the following: 61. Mention the number of cells in the following (a) Middle piece in human sperm. stages: (b) Luteinising hormone in human males. S. No. Embryotic stage No. of Cells [Delhi 2012] (i) Zygote (a) 51. Identify A, B, C and D with reference to (ii) Morula (b) gametogenesis in humans, in the flow chart given below:[All India 2012 C] (iii) Blastocyst (c) GnRH [Delhi 2011] LH FSH 62. Name the embryonic stage that gets implanted in human female. Explain the events that occur AB during this process. [All India 2011 C] Androgens Factors 63. (a) Name the human embryonic stage shown below. Identify ‘A’ and ‘B’ in it. CD A 52. Name the labels (a), (b), (c), (d), (e), (f) in the diagram of seminiferous tubule. [Delhi 2011] B (e) (c) (b) Mention the part of the above embryonic stage (d) (b) that forms the foetus. [All India 2010 C] (f) 64. Where is morula formed in humans? Explain the process of its development from zygote. [Delhi 2009] 65. (a) Where do the signals for parturition originate (a) from in humans? 53. Draw a labelled diagram of a Graafian follicle. (b) Why is it important to feed the newborn [All India 2008] babies on colostrum? [All India 2012] Human Reproduction  47

66. Why is parturition called a neuroendocrine 77. Draw a diagram of structure of human ovum mechanism?[All India 2011 C] surrounded by corona radiata. Label the following parts: 67. What is colostrum? Why is it important to be given to the newborn infants? [Foreign 2009] (i) Ovum (ii) Plasma Membrane 3 Marks Questions (iii) Zona Pellucida 68. Explain the steps in the formation of an o v u m State the function of Zona Pellucida. [Delhi 2013] from an oogonium in humans. 78. Draw a labelled diagram of microscopic structure  [All India 2009 C, 2013] of human sperm. 69. Mention the target cells of luteinising hormone [Delhi 2008, 2009 C, Foreign 2011] in human males and females. Explain the effect 79. Draw a diagram of the microscopic structure of and the changes which the hormone induces in human sperm. Label the following parts in it and write their functions. each case. [Delhi 2009 C] (a) Acrosome (b) Nucleus 70. Draw a sectional view of human ovary. Label the following parts: (c) Middle piece [Delhi 2013] (i) Primary Follicle (ii) Ovum 80. Write the function of each of the following: (a) Seminal vesicle (b) Scutellum (iii) Graafian follicle (c) Acrosome [Delhi 2012] (iv) Corpus luteum [All India 2009 C] 81. Explain the events in a normal woman during 71. Describe the process of parturition in humans. her menstrual cycle on the following days : [Delhi 2015] (a) Ovarian event from 13-15 days 72. Draw a diagrammatic, labelled sketch of a sectional view of human ovary. [Foreign 2015] (b) Ovarian hormones level from 16 to 23 days 73. Name and explain the role of inner and middle (c) Uterine events from 24 to 29 days. walls of the human uterus.[Delhi 2014] [Delhi 2015 C] 74. Draw a diagrammatic sectional view of a human 82. Explain the events in a normal woman during seminiferous tubule and label sertoli cell, primary her menstrual cycle on the following days : spermatocyte, spermatogonium and spermatozoa (a) Pituitary hormone levels from 8 to 12 days. in it? [All India 2013] (b) Uterine events from 13 to 15 days. 75. The given diagram shows (c) Ovarian events from 16 to 23 days. human male reproductive [All India 2015 C] system (one side only). 83. Study the figure given below and answer the following questions: (a) Identify ‘X’ and write its location in the body. Y (b) Name the accessory gland Inner cell mass ‘Y’ and its secretion. Z (c) N a m e a n d s t a t e t h e function of ‘Z’.  X A [Delhi 2015 C] 76. This diagram below shows (a) Name the stage of human embryo the figure a part of the human female represents. reproductive system. (b) Identify ‘A’ in the figure and mention its Z function. (c) Mention the fate of the inner cell mass after implantation in the uterus. X (d) Where are the stem cells located in this Y embryo?  [Delhi 2009] (a) Name the gamete cells that would be present 84. Name the stage of human embryo at which it gets in ‘X’ if taken from a newborn baby. implanted. Explain the process of implantation. [Delhi 2015] (b) Name ‘Y’ and write its function. (c) Name ‘Z’ and write the events that take place 85. Women are often blamed for producing female children. Consequently, they are ill treated here. [All India 2015 C] and ostracized. How will you address this issue scientifically if you were to conduct an awareness programme to highlight the values involved? [Delhi 2014] 48 Biology–12

86. Draw the following diagram related to human (b) Specify the sources of the hormones mentioned reproduction and label them. in the graph. [All India 2008] (a) The zygote after the first cleavage division 99. Enumerate the events in the ovary of a human (b) Morula state female during: (c) Blastocyst stage.  [Delhi 2013] (a) Follicular phase, 87. Draw a labelled diagram of the embryonic stage (b) Luteal phase of menstrual cycle. [Delhi 2011] that gets implanted in the human uterus. State the functions of the two parts labelled. 100. With the help of graphical illustration only, show the changes in the levels of the pituitary hormone [Foreign 2016] during a menstrual cycle in humans. 88. Draw a labelled diagram of the sectional view of [Delhi 2011 C] the seminiferous tubule of a human. 101. Briefly explain the events of fertilisation and [All India 2008, Delhi 2010, 2014, Foreign 2015] implantation in an adult human female. 89. Differentiate between the location and function of Sertoli cells and Leydig’s cells. [Delhi 2016] [All India 2010 C] 102. List and explain the events that follow the journey of human zygote until its implantation. 90. Draw a labelled diagram of human sperm. [Foreign 2015] [Delhi 2013 C] 91. Draw a diagram of human sperm. Label only 103. Draw a diagram of a mature human sperm. Label those parts along with their functions, that assist any three parts and write their functions. the sperm to reach and gain entry into the female [CBSE 2018] gamete.  [Foreign 2014] 5 Marks Questions 92. Explain the hormonal control of spermatogenesis 104. (a) Draw a diagrammatic sectional view of the in humans. [Foreign 2014] female reproductive system of human and label the parts: 93. Describe in sequence the process of sperma- togenesis in human. [All India 2010] (i) Where do the secondary oocytes develop? (ii) Which helps in collection of ovum after 94. Draw a diagrammatic sectional view of human ovary to show the development of follicles and ovulation? ovulation. Label the different stages in the diagram.[Delhi 2008, 2009, 2010 C] (iii) Where fertilization occurs? 95. Where does sperm mature and become motile? (iv) Where implantation of embryo occurs? [All India 2008 C] (b) Explain the role of pituitary and the ovarian 96. Explain the role of pituitary and the ovarian hormones in menstrual cycle in human hormones in menstrual cycle in human females. females.[Delhi 2013] [Delhi 2013] 105. (a) How is 'oogenesis' markedly different from 97. When does the corpus luteum degenerate? 'spermatogenesis' with respect to the growth Explain the immediate consequences of its till puberty in the humans? degeneration in human female. (b) Draw a sectional view of human ovary and label the different follicular stages, ovum and [All India 2013 C] corpus luteum. [Delhi 2014] 98. (a) 106. (a) Draw a labelled diagrammatic view of human male reproductive system. Ovarian hormone levels Estrogen (b) Differentiate between: Progesterone (i) Vas deferens and vasa efferentia (ii) Spermatogenesis and spermiogenesis [Delhi 2014] 107. Explain the different phases of menstrual cycle and correlate the phases with the different levels, of ovarian hormones in a human female. 1 5 10 15 20 25 29 [All India 2014 C] Days 108. Write the specific location and the functions of Read the graph given above and correlate the the following cells in human males: uterine events that take place according to the hormonal levels on (i) Leydig cell (ii) Sertoli cells (i) 6–15 days (ii) 16–25 days (iii) Primary spermatocyte. (iii) 26–28 days (if the ovum is not fertilised) Explain the role of any two accessory glands in human male reproductive system. [Delhi 2011] Human Reproduction  49